A literature review requires a comprehensive, structured search across recommended resources for your topic. Evidence-based research and clinical decision-making depend on the quality of your literature search and the resources you choose. The library provides a range of resources including databases, point-of-care clinical summaries, journal articles, books and e-books. A systematic literature review gathers background information from the clinical summaries; prevalence and context from grey literature sources; and a set of relevant journal articles found in recommended medical and nursing databases. This guide recommends the key resources for each subject area, and how to search them in a comprehensive and systematic way. It helps you to structure your research question, fine-tune your database search technique, appraise your results, and write up your search strategy. The Databases section provides step-by-step instructions for specific databases, and the Grey Literature section highlights useful sources.
Choosing relevant resources for your topic
A full list of all library databases, clinical summaries, journal collections, and e-book collections are listed on our A-Z Resources page. Selecting the best resources for your topic means using key databases listed on our Recommended Resources list above for different subject areas, as well as sources relevant to your clinical specialty.
Clinical Summaries are point-of-care tools that provide expert summaries of clinical conditions in all the specialties. They cover definitions, prevalence, diagnosis, management, complications, international clinical guidelines and patient information on each condition. DynaMed, UpToDate and BMJ Best Practice collate information from a variety of reputable sources including journal articles, clinical textbooks, and professional organisations. You can do a basic search for a clinical specialty, or you can search for a specific condition or surgical procedure. These resources are a good starting point for writing a literature review as they provide content that may be useful for introduction and context.
Databases are lists of articles that are published in journals worldwide, and they usually provide the author’s abstract summarising the article, and sometimes provide a link to full text. You can do a Basic or Advanced search in the databases. A Basic search may be sufficient for undergraduate assignments, while the Advanced search options ensure your search is comprehensive and your results are relevant if you are writing a literature review or a systematic review. The best databases for medicine, nursing and allied health are listed in the table above. PubMed and Medline have the same content, so you can choose either. Medline records are contained within Embase, so we recommend that you search PubMed or Medline first, and then search Embase and use a filter to remove the Medline records. See the Databases – Embase guide for further explanation.
Citation Databases are helpful if you want to check if articles you found in the key databases have been cited (referred to) by other more recent articles. PubMed has a citation feature listing citations for each article found, and Scopus is a large citation database where you can search for a specific article title to find other articles that have cited it.
Journal Collections such as Science Direct and Springer Link are large collections of journals from different publishers. You can search these collections individually. The content is usually also listed in PubMed/Medline or Embase, so you may find many articles that you already found in your database searches.
E-Book Collections gather together useful books on particular topics, such as research methods in the Sage Research Core Collection; prescribing guides and BNF in Medicines Complete; and clinical textbooks in Access Medicine, Access Physiotherapy, Ovid E-books, Clinical Key, and Ebsco E-books. A complete list of all print books and e-books in RCSI libraries is available to search in our Primo library catalogue search.
Grey Literature is anything that is not published in a journal, so this includes statistics and reports from sources and organisations such as Departments of Health, HSE, World Health Organisation, newspapers, clinical trial registers. Many grey literature sources can be found through google searches and from sources listed on our comprehensive guide to Grey Literature.
The first step is to clarify your topic and write your research question. Your topic may have a few different aspects to it, and there may be different words and synonyms for each concept. It is helpful to list all the synonyms/alternative terms and to group them by concept. You will be searching for each concept separately in the databases. This approach helps to identify gaps in the literature and highlight which aspects of your topic are well-researched, and which aspects are under-researched. It is good practice to keep a record of your search terms as you may review and amend your search strategy over time.
Sample research question grouping keywords/synonyms within different concepts:
How does pain management impact on cancer patients’ quality of life?
There are three different concepts within this question:
It may be useful to do a quick basic search in PubMed to begin with, for cancer pain quality of life, and browse some initial results in order to identify the commonly used keywords or Mesh Terms for each concept. Then list the keywords, synonyms, and phrases for each concept separately:
Keyword searches will find articles that mention your own words at least once, anywhere in the article. Your keyword searches will be more effective by using these options:
Phrase searching to find an exact phrase: add inverted commas to find your words beside each other in the same sentence: for example: "reflective practice"; "chest pain"; "hand washing”. If you don’t use inverted commas, the databases may look for your words separately rather than as a concept. If you decide to use inverted commas, you will not find the words in a different order, for example “pain management” won’t find “management of pain”.
Field Searching: you can choose to search for your keywords anywhere in an article record [All Fields], or only in the Title or Abstract fields [Title/Abstract]. Title/Abstract searches usually find a smaller set of results that are more relevant, but they depend on the specific words being used in the title or abstract. You may miss some potentially relevant articles if your specific keywords are not mentioned in the title, or if the publisher has not provided an abstract.
Truncation to find alternative word endings: add * or $ to the word stem to find different word endings: e.g., transplant* will find transplant, transplants, transplanted or transplantation. Check the database Help to see whether it uses the * or the $ for truncation. Be careful about finding words you don’t want, for example nurs* would find nurses, nurse, nursing, as well as nursery. PubMed requires at least four letters in the word stem.
Proximity searching: will find words located near each other - check each database Help section for syntax to use for proximity or adjacency searching.
After identifying the keywords and phrases for each concept within your topic, it is good practice to search for Subject Headings to ensure your search is comprehensive. Every database has a thesaurus of subject headings that are added to articles to describe the main topics of the paper. You can search for subject headings manually by browsing the thesaurus. Or you can use suggest/mapping functions so that the database will automatically find subject headings that match your keywords, and allowing you to select relevant ones to add to your search.
| Database | Subject Headings |
Mapping Options |
Field Code |
| PubMed | MeSH (Medical Subject Headings) |
Basic Search automatically maps your keywords to MeSH terms and includes both in the search. Advanced Search – click on MESH, select MeSH terms, click Add to Query Builder, select OR for similar terms, click Search PubMed to run the search. |
[MeSH] |
| Embase | Emtree |
In Emtree search for your keywords and select the best matching terms from the list. Click Add to Search Builder for each term you want, using OR between them, then click Take to Advanced Search to run the search. Alternatively, in Advanced Search – click Mapping tab, select Map to preferred term in Emtree and select Search also as free text in all fields, type in your keywords, then select the best matching Emtree terms, and Take query to the Advanced Search. |
|
| CINAHL | CINAHL Headings | Suggest Subject Terms, type in your keywords, select the best matching terms, choose OR to combine similar words, click Search Database. | MH |
| PsycInfo | APA PsycInfo Index of Psychological Terms | Suggest Subject Terms, type in your keywords, select the best matching terms, choose OR to combine similar words, click Search Database. | DE |
Start by combining similar words with OR to find all the articles about each concept separately.
Then combine different concepts with AND in your Search History, for example:
| Search # | Concept (include your keywords, phrases, subject headings) | Sample Results |
|---|---|---|
| S1 | pain OR “pain management” OR Pain [Mesh] OR Pain Management [Mesh] | 1000 |
| S2 | cancer OR oncology OR neoplasm OR neoplasms OR “cancer patients” OR Neoplasms [Mesh] OR Cancer Patients [Mesh] | 2000 |
| S3 | “quality of life” OR Quality of Life [Mesh] | 500 |
| S4 | S1 AND S2 AND S3 | 45 |
This approach to your literature search is comprehensive and clearly structured and highlights which concepts are well researched, and which aspects are less well-researched. Interpreting your search results may support a recommendation for further research on specific aspects of your topic. This structured approach is required if you are writing a systematic review.
Every database has options to add Limits/Filters to reduce and focus your results, for example limiting to the latest 5 publication years, or limiting to a patient age group. Limiting to English language will create a bias in your research and will eliminate articles that were published in different languages and later translated to English. Limiting results to Full Text is not recommended as it will omit many potentially relevant articles from your result set if the full text is not provided within the database.
You may add filters for particular research methods, for example narrowing your results to systematic reviews, meta-analyses, qualitative or quantitative research, RCTs, case studies etc. You may add research methods as an extra concept within your search history by searching for keywords and subject headings relating to the particular research method you specify. Research Methods information is available in the Sage Research Collection available on the Library A-Z Resources list. It is good practice to briefly scan the article titles found in the main result set before adding any filters, to be sure you don’t miss anything important in the main result set before the filter was applied.
After you have completed your literature searching, you will scan the results and select the most relevant articles for your topic. You can enhance the quality of your literature search by doing additional Known Author and Citation searches.
A Known Author search is where you search for an author name using the Author field option in the database. When you screened your search results to select relevant articles to include in your review, you may have noticed particular author names appearing frequently or you may already be aware of known experts in the field. You can run an author name search in each of the relevant databases you have selected for your topic.
Citation searches are important, particularly if some of the relevant articles you found in your search were published two or more years ago. To run a Citation search, open Scopus from the library A-Z Resources list, and copy and paste the exact title of an article into the search box. When you find the article, click on the number in the CITED BY column. This shows a list of more recently published articles that cite or refer to the older article.
Every database has a Sign In option to create a personal folder and save your searches. This provides an accurate record of your search history, ensuring that your research is transparent and can be replicated. Keeping this record helps you to write up your search strategy, and means you can re-run or easily amend your search history if you decide to change your topic. You can add relevant articles to your folder for future reading, or to Export a set of articles to reference management software such as EndNote. It can be useful to export results from each database into EndNote to de-duplicate results if you have large quantities of results from multiple databases. Another option for de-duplicating your results is to search Medline, Cinahl, and PsycInfo from one publisher (Ebsco) where the results will be automatically de-duplicated for you.
Critical Thinking (awareness or engagement) means to analyse the information we encounter, to ask questions about the information resources we read, and not accept what we read or hear at face value. This extends from what we read online or in books, to published research and articles found in the library databases. Critical Thinking is a skill for life as we are surrounded by information and sometimes, misinformation. You can demonstrate you have the ability to weigh up different arguments and perspectives, and use evidence to help you form your own opinions, arguments, theories and ideas.
Critical Appraisal in the healthcare research context means using your judgement and a checklist to assess the validity and relevance each article you found in your literature search. As you screen your results for relevance using your Inclusion and Exclusion criteria it may be helpful to begin identifying recurring themes. CASP Checklists are an excellent source for critical appraisal of systematic reviews, meta-analyses, RCTs, qualitative and quantitative research articles in medicine and nursing. They are available to download here:
https://casp-uk.net/casp-tools-checklists/
© University of Plymouth
The Critical Process supports undergraduate learning at university, allowing you to really analyse information, form your own conclusions, and write about your own understanding and application of knowledge. Additional resources include:
Critical Thinking Skills interactive resource (requires Moodle login)
RADAR Rationale, Authority, Date, Accuracy, Relevance framework (requires Moodle login)
Critical Thinking in the AI context on the Library Guide to AI.
This example of how to write up your search strategy can be amended to suit your own topic. Items in italics and brackets are optional, so you can add in what is required or relevant in your own write-up. It can be useful to look at standard formats for search strategy paragraphs in articles published in your field and in particular journals you'd like to publish in, some references are listed below.
"A comprehensive literature search was conducted in PubMed, Embase (include the platform if appropriate eg Elsevier / www.embase.com), PsycInfo (Ebsco or Ovid platform as appropriate) and Cochrane databases using keywords, synonyms and subject headings (insert date if required eg: in April 2022 / on 25th April 2022). MeSH headings were used in PubMed and Cochrane, Emtree headings were used in Embase, and APA Psychological Terms were used in PsycInfo. Separate searches on each aspect of the topic found that there were large numbers of papers published on each topic. When the searches were combined there were very few results, indicating a gap in the literature and suggesting the need for further research on the impact of anti-depressants on quality of life for cardiac patients. No language filter was applied as this would create a bias in the literature review as it would automatically exclude potentially useful articles that were originally published in other languages. A date limit of 5 years was applied to the result set in order to focus on recent research. A total number of xx papers were found in the database searches, following the removal of xx duplicates, of which xx were selected for inclusion using the following inclusion and exclusion criteria: (insert your exclusion and inclusion criteria here if appropriate). Additional relevant papers were identified through reference searching, citation searching in Scopus or PubMed, and grey literature searches using Google Scholar and relevant national and international sources including HSE and Lenus, NHS, Department of Health, WHO and patient organisations websites and reports (delete/add in whatever sources you had used). A PRISMA chart (see appendix) provides further detail on the search strategy results. The literature search indicated that extensive research has been published on patients' quality of life generally, and on quality of life in relation to depression, but very little of this is focused on cardiac patients in particular. (You may be required to outline how this relates to your current setting / hospital setting / community setting / the need for further research on this in your own work setting). This (narrative / systematic / scoping / literature etc) review provides an overview of the key themes arising from the literature found, critically appraises the literature, and highlights areas needing further research for the improvement of (patient care / quality of life for this cohort etc)."
Sample search strategies in published articles:
Carroll P, Dervan A, Maher A, et al. (2021) Patient and Public Involvement (PPI) in preclinical research: A scoping review protocol. HRB Open Res. 4:61. https://pubmed.ncbi.nlm.nih.gov/34522837/
Fortune J, Murphy P, Merchant N, Kerr C, et al. (2020) Transition from child-centred to adult-oriented healthcare systems for young people with neurodisability: a scoping review protocol. HRB Open Res. 3:61. https://pubmed.ncbi.nlm.nih.gov/33215059/
Spooner M, Duane C, Uygur J, et al. (2022) Self-regulatory learning theory as a lens on how undergraduate and postgraduate learners respond to feedback: A BEME scoping review: BEME Guide No. 66. Med Teach; 44(1):3-18. https://pubmed.ncbi.nlm.nih.gov/34666584/