During your PhD, you will need to interact with previous research for various tasks and purposes. This section will show you different approaches and techniques to find and retrieve the research you need.

On this page you will find information on the following:

  • Creating complex database searches for your research questions
  • Reference databases and search engines
  • Search techniques and management
  • Tracing references, citation searches and following researchers
  • Access to reference databases and full-text subscriptions
  • Support services at your library

Creating complex database searches for your research question

When searching databases you need a search strategy that matches your research question. It is a good idea to divide the question into components, and to create search subsets for each component. The combination of these subsets will be your search strategy. Your research question may involve several elements, such as the methods you will employ, the topic of inquiry, and possibly the setting. For some research questions, it is useful to have more than one search strategy.

Search approaches vary across disciplines and research fields. In medicine, there may be a need for a systematic search for a review ahead of a clinical trial, whereas searching in the humanities and social sciences is part of the research process itself. While there is no one method to fit all search needs, there are some common techniques that can be employed in most reference databases.

Reference databases and search engines

"I consider it extremely important to be as in touch with the literature as possible of course." PhD candidate

Bibliographic databases differ from internet search engines with regard to both subjects covered and search functionality. In addition to basic bibliographic information, they may include abstracts, full texts, citations and other valuable descriptors of content. Bibliographic databases typically add value by supplying controlled search vocabularies, which are needed for systematic searching.

Published research is indexed in bibliographic reference databases. These databases are designed to allow our searches to be documented, transparent and reproducible, building on the same principles as other aspects of our research. Search engines for everyday information adapt to us and our information needs, therefore searching for research publications can feel more cumbersome.

When your purpose is to identify the seminal literature of your field, search engines such as Google Scholar offer convenient features to provide you with an initial overview. However, when your aim is a more thorough search, you need to search specialized bibliographic databases. Diligent use of both options will enable you to discover the richness of the literature in your field.


  • Bibliographies: you can search previous publications. They exist in both print and online format, but usually have limited scope.
  • Catalogues: you can search collections in institutions like libraries and archives.
  • Discovery systems: you can search collections across platforms. Typically all content made available in a library.
  • Reference databases: you can search in previously published research, most commonly journal articles. Searches can be discipline-specific or general.
  • Search engines: these search the open web, not the deep web.


The example below shows a bibliographic record from the database PsycINFO, and the fields of the record show us what is indexed when a reference is added to the database. Knowing how an article is indexed can aid us in developing efficient search strategies.

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Accession Number: 2016-30160-003
Title: Parental divorce and initiation of alcohol use in early adolescence. [References].
Publication Date: Jun 2016
Year of Publication: 2016
Publication History: Accepted: Jan 2016
Revised: Jan 2016
First Submitted: Oct 2015
Language: English
Author: Jackson, Kristina M; Rogers, Michelle L; Sartor, Carolyn E.
E-Mail Address: Jackson, Kristina M.:
Correspondence Address: Jackson, Kristina M.: Department of Behavioral and Social Sciences, Center for Alcohol and Addiction Studies, Brown University, Box G-S121-4, Providence, RI, US, 02912,
Institution: Jackson, Kristina M.: Department of Behavioral and Social Sciences, Center for Alcohol and Addiction Studies, Brown University, Providence, RI, US

Rogers, Michelle L.: Hassenfeld Child Health Innovation Institute, Brown University, Providence, RI, US

Sartor, Carolyn E.: Department of Psychiatry, Yale University School of Medicine, New Haven, CT, US
Source: Psychology of Addictive Behaviors. Vol.30(4), 2016, pp. 450-461.
Publication Month/Season: Jun
NLM Title Abbreviation: Psychol Addict Behav
ISSN Print: 0893-164X
ISSN Electronic: 1939-1501
Other Serial Titles: Bulletin of the Society of Psychologists in Addictive Behaviors, Bulletin of the Society of Psychologists in Substance Abuse
Publisher Information: American Psychological Association; US
Other Publishers: Educational Publishing Foundation, US; Society of Psychologists in Addictive Behaviors
Format Covered: Electronic
Publication Type: Journal; Peer Reviewed Journal
Document Type: Journal Article
Abstract: Parental divorce/separation is among the most commonly endorsed adverse childhood events. It has been shown to increase subsequent risk of alcohol dependence and problems across adolescence and early adulthood, but its influence on early stages of alcohol involvement has only recently been explored. In the present study, we examined whether time to first full drink was accelerated among youth who experienced parental divorce/separation. To determine specificity of risk, models controlled for perceived stress as well as family history of alcoholism, current parental drinking, and internalizing and externalizing problems. Developmental specificity in terms of timing of both parental divorce and first drink was also examined. Participants were 931 middle-school students (488 girls, 443 boys) who were enrolled in a prospective study on drinking initiation and progression (52% female; 23% non-White, 11% Hispanic). Students indicated whether and at what age they had consumed a full drink of alcohol. Parental divorce/separation was coded from a parent-reported life-events inventory and was grouped based on age experienced (ages 0-5, ages 6-9, age 10+). Cox proportional hazard models showed increased risk for onset of drinking as a function of divorce/separation, even controlling for stress, parental alcohol involvement, and psychopathology. There was no evidence for developmental specificity of the divorce/separation effect based on when it occurred nor in timing of first drink. However, the effect of parental divorce/separation on initiation was magnified at higher levels of parental drinking. Given the rates of parental divorce/separation and its association with increased risk of early drinking, investigation of the mechanisms underlying this link is clearly warranted. (PsycINFO Database Record (c) 2016 APA, all rights reserved)

Digital Object Identifier:
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Key Concepts: divorce, childhood, adolescence, alcohol, initiation

Subject Headings: *Alcohol Drinking Patterns
Adolescent Development
Childhood Development

PsycINFO Classification Code: Drug & Alcohol Usage (Legal) [2990]

Population Group: Human; Male; Female.
Childhood (birth-12 yrs); School Age (6-12 yrs); Adolescence (13-17 yrs)
Location: US
Methodology: Empirical Study; Longitudinal Study; Prospective Study; Quantitative Study

Tests & Measures: Coddington Life Events Questionnaire for the Elementary Age Group
Perceived Stress Measure
Family History of Drinking Problems Measure
Alcohol Use Disorders Identification Test
Child Behavior Checklist
Test DOI: Alcohol Use Disorders Identification Test [doi:
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] (9999-01528-000) [PsycTESTS Record Link for subscribers]
Grant/Sponsorship: Sponsor: National Institutes of Health. US
Grant: R01 AA016838 and K02 AA13938
Recipient: Jackson, Kristina M.

Sponsor: National Institutes of Health. US
Grant: K08 AA017921
Recipient: Sartor, Carolyn E.

Copyright: HOLDER: American Psychological Association
YEAR: 2016
Cited References: Achenbach, T. M. (1978). The Child Behavior Profile: An empirically based system for assessing children's behavioral problems and competencies. International Journal of Mental Health, 7, 24-42.
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Finn/bestill i Oria Finn/bestill i Oria

Amato, P. R. (2000). The consequences of divorce for adults and children. Journal of Marriage and the Family, 62, 1269-1287.
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Bibliographic Links Finn/bestill i Oria

Amato, P. R. (2001). Children of divorce in the 1990s: An update of the Amato and Keith (1991) meta-analysis. Journal of Family Psychology, 15, 355-370.
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Bibliographic Links Finn/bestill i Oria


An increasing number of search engines provide scholarly content. They can be excellent for the efficient retrieval of information. In particular, Google Scholar offers convenient, simple access. The service also provides links to your library holdings and information about citing documents in both Google Scholar itself and Web of Science. However, remember that

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  1. Even though the advanced search option in Google Scholar allows for searching by specified bibliographic information, such as author and year of publication, you may still not be able to access the information you need. Searching by specific bibliographic information assumes that the information has been included, for example by author or year. Since this is done automatically, mistakes occur, and consequently information is missed.
  2. It is unclear which content is actually being indexed. Because of limited storage capacity and retrieval speed, information is indexed only to a certain extent. Therefore, do not expect to find everything by using search engines. A large number of publications remain invisible when they are:
  • Not posted on the web
  • Not linked to and therefore not found by a crawler
  • Placed beyond paywalls
  • Hidden in databases
  • Located within private sites of organizations, governments and companies
  • Not found because of your personal settings
  • Listed beyond the first pages

Search techniques and management

Databases offer a variety of options such as filtering and sorting, expanding or limiting, and specific search techniques like applying wildcards, phrase searches, operators and use of search strings or search history to aid in the development and execution of the search.

Specific search techniques

There is some variation between databases as to what kind of search functionality they support. In the following, you will find a description of common functionality available in most databases. You can always check the help section of the database for information on search functionality.


Wildcards help you include alternative spellings or word forms. A wildcard replaces character(s) of a word to enable searching for variations in spelling. When used to search with word stems, we call it truncation.

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Frequently used wildcard characters are *,?, #, $. Here are three possible examples:
Example 1: Truncation: searching with the word stem.
child* matches children, child, childhood, childish, etc.
Example 2: Sometimes you can use a wild card at the beginning of the word to include variations.
*oxide yields peroxide, sulphoxide, nitroxide, etc.
Example 3: Wild cards can replace characters in your search word. This is useful to capture spelling differences, typically between British and American English.
Colo?r matches both color and colour.


When you search for a specific phrase, enclose the phrase with double quotation marks (“…”). This narrows your search to those exact words in that specific order. Examples: “United Nations”, “breast cancer”


Boolean operators
The use of AND, OR and NOT, called Boolean logic, helps you to combine your search words.

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Combining keywords with AND will retrieve a search result that includes all your search words.
Example: influenza AND “vitamin C”
Combining keywords with OR will retrieve at least one of your search terms. This is useful when you want to include synonyms or related terms and are interested in either of the words.
Example: influenza OR “common cold”
Combining keywords with NOT will exclude search words from your result. Use this with great caution, as you cannot control what is excluded from the result.
Example: “common cold” NOT “vitamin C”


These operators let us search for keywords that express relationships, as in words that often appear together, but are not fixed expressions. By using proximity operators, we can specify the order of words and the number of words that can separate them. Most databases have proximity operators, but the commands used vary from one database to the next. Below you will find some examples of proximity operators.

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  • NEAR = near operator. Add a number to define how many words may separate your search words. Example from Web of Science: tax NEAR/5 reform returns hits containing the words tax and reform within a five-word distance.
  • N = near operator. Retrieves hits containing the words regardless of the order in which they appear. Add a number to define how many words may separate your search words. Example from SocIndex (Ebscohost): tax N5 reform finds records containing the words tax reform as well as reform of income tax.
  • W = within operator. Retrieves records with the words in the order you entered them. Add a number to define how many words may separate your search words. Example from SocIndex (Ebscohost): tax W8 reform finds records containing tax followed by reform within 8 words, but not e.g. reform of income tax.
  • ADJ = adjacent operator. Retrieves records with the words regardless of the order in which they appear. Add a number to define how many words may separate your search words. Example from Medline (OvidSP): tax ADJ4 reform retrieves tax reform as well as reform of income tax.


By enclosing your search terms in parentheses, and using Boolean and proximity operators you can combine several keywords and build complex search strings. Remember that expressions in inner parentheses are searched first. Example: (("common cold" OR influenza) AND (garlic OR vitamin* OR "antiviral treatment"))


As search strings can be difficult to read for searches with many elements, most databases have the functionality of combining searches through search history. In bibliographic databases all searches you do will be remembered by the database for the duration of your search.

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You can go back and look at the hits of a previous search to compare the different search results. The search history lets you combine previous searches.
Search 1: influenza OR “common cold”
Search 2: “vitamin C” OR garlic OR antibiotics
Search 3 : Search 1 AND Search 2 (combining Search 1 and Search 2). This technique is often used in systematic reviews.


When you search for a document by a specific author, be aware that author names are presented in different ways across databases. Names might not be given in their full form; for instance, they may be presented with last name and initials only and will therefore only be searchable as such.

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For the most complete result, a good strategy is to search for all possible variations of a name. Use wildcards to include different types of spelling.

  • Spaces, apostrophes or hyphens:
    Search both O’Leary and OLeary for the author O’Leary.
  • Different alphabets:
    Search Grønås, Gronas or Gr*n*s for the author Grønås.
  • Namesakes/homonyms:
    People with common names are difficult to distinguish from namesakes, especially when only the last name and initials are recorded instead of the full name. Some databases group authors by affiliation and research area, making it easier to find the right author.

Searching by topic

Topic information is typically found in titles, abstracts, keywords or subject headings. Using keywords that describe your topic is an efficient way of searching. This kind of searching is often referred to as text word searching.

You should note that different keywords are used to describe the same phenomenon, and conversely, the same keyword may be used to describe very different phenomena. You will therefore need to think about relevant synonyms when searching. Using a thesaurus or subject heading will help you do this.

Utilizing a thesaurus

Some subject-specific databases maintain a controlled, hierarchical vocabulary to support your search. Searching the controlled vocabulary from a thesaurus is useful because it covers synonyms and closely and distantly related keywords.


  • ERIC (ERIC thesaurus (subjects))
  • Sociological Abstracts (Sociological thesaurus (subjects))
  • PsycINFO (PsycINFO subject headings)
  • PubMed and Medline (Medical Subject Headings – MeSH)
  • Embase (Emtree)
  • CINAHL (CINAHL headings)
  • ASFA
  • MLA International Bibliography (MLA Personal Names Thesaurus and MLA Subjects Thesaurus)
  • The Philosopher's Index Thesaurus

Searching by research method

Make the remaining list of retrieved documents as relevant and precise as possible, familiarize yourself with the database that serves your area of interest and check whether you can apply specified filters to narrowing your search. You may, for example, filter your search by

  • research method
  • demographic variables
  • interventions used
  • outcome measures

Search management

Reference databases have functionality that allows you to manage your search and the search results.


Database vendors allow users to create accounts. Once you have an account, you can save your search in the database. If you have created a complex search, saving it will allow you to run the search again without having to type it all in again.


A long list of search results may be hard to browse and evaluate. Sorting and/or filtering the list might be useful.

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You can sort results by:

  • Year of publication
  • Title of the publication
  • Relevance
    Here, relevance relates to the occurrence, and the frequency of occurrence, of your particular search terms in the title, keywords, abstract, full text and, if selected, your personal field of research.
  • Number of times cited
    The number of times a document has been cited is often understood to reflect its influence or impact. This might be useful to gain an understanding of how often the document has been read by researchers in the field. However, there are few databases that offer options for tracking references and citations and for sorting by ‘times cited’. Keep in mind that the number of citations is not necessarily a measure of quality or importance. You can read more about this in the Citation impact section.

Filter results by:

  • Subject
    Refine search result by specified subjects.
  • Author
    Refine search result by contributing authors. This option provides you with key authors in the field.
  • Publisher and journal
    Refine search result by publisher or journal. This option provides you with key publishers and journals.
  • Date of publication
    The date filter allows you to refine by defined periods of publication.
  • Library or database holdings
    Refine the search result by the holdings of your library or the content of specific databases.


Two key terms in searching are sensitivity and specificity. High sensitivity casts the net wider; you try to find as much as possible of the relevant research literature, but you will also retrieve irrelevant hits in the databases. High specificity will make your search precise and relevant, but you may lose some of the relevant literature.
Depending on your need, you can use the following approaches:

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To expand your search

  • search various databases and other sources
  • employ general terms and synonyms or related terms
  • use wildcards
  • combine terms by using OR
  • search the full text when available

To limit your search

  • use subject specific database
  • use phrases
  • search by using specific keywords
  • search by specified information such as author or topic
  • apply available filters
  • if available, use a thesaurus
  • combine terms by using AND or NOT


If your results list yield many relevant hits, you will no doubt like to save these results for further use. You can save the result list in your database account. Another option would be to export the relevant results to a reference manager and save them there. The latter option allows you to use the results in your own writing.


Literature databases, publisher and journal websites, research blogs and social networks all provide newsfeeds (RSS) and research activity alerts which help you keep updated on recent research publications and developments in your field. Look for the following options:

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  • Saved search alerts
    Most databases have alert services which enable you to save your search query. They offer e-mail alerts and subscription feeds to let you know whenever new content that matches your query is added.
  • Citation alerts
    Services which keep track of references offer e-mail alerts and subscription feeds to let you know whenever a particular work or author is cited. Check whether the database or journal of interest provides this service.
  • Table of contents alerts
    In general, journals offer table of contents alerts and subscription feeds. Signing up for this enables you to receive an alert whenever new content is added.
  • New books
    Some libraries and publishers offer e-mail alerts and subscription feeds on new books.
  • Online networks and research blogs
    Online networks and blogs where researchers post and discuss recent findings are valuable arenas to keep up with current research developments. Typically, blogs come with subscription feeds, and are re-distributed through different social networks such as Twitter and Facebook. Mendeley and are examples of networks aiming at sharing scholarly references, alerting you and your followers whenever your research has been viewed or commented on, or new publications have been added.

Tracing references, citation searches and following researchers

"I use bibliographies of other books a lot. If I have a good book that is related to what I’m doing, then I always carefully read the bibliographies." PhD candidate, social sciences

Tracing references is an efficient way of identifying relevant literature for your doctoral thesis. References connect present findings with previous findings and put pieces of knowledge into a wider context. Cited or citing documents allow us to follow a discussion or development of a subject over time. Scholarly databases, such as Web of Science, Scopus and Google Scholar, are designed for tracing citations. These services give information on how often a document has been cited and by whom. How frequently a document has been cited is considered indicative of its impact and use by other researchers. You can use features in these so-called citation databases to:

  • Trace the references given in the literature you are currently reading
  • Check other documents that have cited your document of interest

Some databases, in particular book catalogues, do not incorporate citation networks. Some may, however, provide statistical information on usage, such as counts of clicks and downloads. Usage measures may give you hints about the impact of a specific document and enable you to figure out trends or directions in a particular research area, and might therefore be helpful in your work.

When exploring your research field, it is useful to see who writes about what, and who collaborates with whom. As you read in your field and check reference lists, you will get a feel for this. However, this will take time and sometimes there is too much literature in your field for you to read all that may be relevant. One way around this is to follow the most important researchers in your field. Google Scholar allows the researcher to set up a profile, and will automatically collect and present the researcher's work in the profile. As a researcher, you should monitor this carefully to ensure only your own work is credited to you. When looking at other researchers' profiles, you can ask to be notified when they publish new material, or when someone cites their work.

Access and support

Although much information, including scholarly publications, is openly available on the Internet, the majority of the scholarly resources you will need are subscription-based. These are made available to you by your library.


Click the links to see the databases accessible at your institution. The lists of databases are organized both alphabetically and by subject. They are accessible from everywhere on campus. When you are off campus, check with your institution to find out how you can connect through proxy or VPN technology.

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Western Norway University of Applied Sciences Library

NHH Norwegian School of Economics Library

University of Bergen Library

University of Oslo Library

UiT - The Arctic University of Norway Library

NTNU University Library


Visit your library website to learn about the services offered, such as courses and guidance in literature searching and reference management.

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Western Norway University of Applied Sciences Library

NHH Norwegian School of Economics Library

University of Bergen Library

University of Oslo Library

UiT - The Arctic University of Norway Library

NTNU University Library