In revisia you search several sources at once and duplicates are removed automatically before you start screening. Create your free account.
## Dialnet, the main Spanish-language database Limiting the search to English-language databases introduces language bias and leaves out relevant Ibero-American literature. For reviews carried out in Spain or Latin America, or on topics from that region, you should add Spanish-language databases. The largest is Dialnet. Dialnet is one of the largest Spanish-language bibliographic portals, run by the University of La Rioja. Its coverage is multidisciplinary, with a strong weight in the social sciences and humanities and also in the health sciences, and it includes journal articles, book chapters, theses and conference proceedings from the Spanish-speaking world. Access to the references is free (with more options if you register for Dialnet Plus), although full-text availability depends on each document. It is especially useful for undergraduate theses, master's dissertations and reviews in fields where much of the research is published in Spanish. **How to search Dialnet.** Combine your key concepts in the document search box. Dialnet doesn't support PubMed's advanced Boolean syntax, so run several searches with synonyms and also browse the journals and tables of contents in your field. You can filter by document type (article, thesis, book), year and language, and browse by author or journal to find related literature. **Limits for a systematic review.** Dialnet is the best way to avoid missing Spanish-language research, but its quality control is uneven and its search is less reproducible than that of an indexed database like PubMed or Scopus. Document your strategy carefully and don't use it as your only source. **Exporting.** Each record lets you download the citation (RIS) to bring it into your [reference manager](/en/blog/mendeley-vs-zotero/) and deduplicate it against the other databases. ## Other Spanish- and Portuguese-language databases: SciELO and LILACS ### SciELO SciELO (Scientific Electronic Library Online) is an open-access electronic library that brings together quality scientific journals from Latin America, Spain, Portugal and other countries. Its coverage is multidisciplinary, and its big advantage is free full text. For a review, it adds peer-reviewed regional literature that is often missing from Scopus or Web of Science. ### LILACS LILACS (Latin American and Caribbean Health Sciences Literature) is the reference database for health sciences in the region, coordinated by BIREME/PAHO/WHO. Access is free and you search it with DeCS descriptors (the Spanish and Portuguese counterpart of MeSH). It is the main regional source for biomedical reviews with an Ibero-American focus and complements PubMed very well. ## Subject databases: CINAHL, PsycINFO and Embase General databases are not enough. Almost every review also needs a source specialized in its field, and these are the three most common. ### CINAHL (nursing) CINAHL (Cumulative Index to Nursing and Allied Health Literature) is the reference database for nursing and allied health (physical therapy, occupational therapy, nutrition, and so on). It indexes journals that are not always in MEDLINE and uses its own subject headings. It requires a subscription, usually available through your university library. If your review is about care, skipping CINAHL leaves out important literature. ### PsycINFO (psychology) PsycINFO, from the American Psychological Association, is the specialized database for psychology and the behavioral sciences. It covers clinical, educational and social psychology and related fields, and includes articles, book chapters and dissertations. Access is by subscription. For reviews in psychology or mental health it is the reference subject source, complementing PubMed and the multidisciplinary databases. ### Embase Embase, from Elsevier, is a large biomedical database that complements MEDLINE. Its coverage is especially strong in pharmacology, medical devices and European literature, and its own controlled vocabulary (Emtree) is more detailed for drugs. It requires a subscription. The Cochrane Handbook considers it part of the minimum search for intervention reviews precisely because it captures studies (mainly European and pharmacological ones) that MEDLINE doesn't index. Another source that shows up more and more in protocols is Epistemonikos, a free collaborative database focused on systematic reviews and secondary evidence, useful for finding existing reviews on your question. ## Comparison table (coverage, access, language)  The table below summarizes the main databases for systematic reviews. Use it as a starting point for choosing your combination, not as a substitute for the methodological decision. What matters is that the sources you choose complement each other and cover your field and your region. | Database | Coverage | Access | Language | |---|---|---|---| | PubMed / MEDLINE | Biomedicine and health sciences | Free | English interface (includes articles in several languages) | | Scopus | Multidisciplinary, with citation analysis | Subscription | English | | Web of Science | Multidisciplinary, selective citation core | Subscription | English | | Cochrane Library | Systematic reviews and clinical trials (health) | Partly free, depending on country and institution | English (some summaries translated) | | Dialnet | Multidisciplinary, Spanish-language focus (humanities and social sciences) | Free (references) | Spanish | | SciELO | Multidisciplinary, Ibero-American open access | Free (full text) | Spanish, Portuguese and English | | LILACS | Health sciences, Latin America and the Caribbean | Free | Spanish, Portuguese and English | | CINAHL | Nursing and allied health | Subscription | English | | PsycINFO | Psychology and behavioral sciences | Subscription | English | | Embase | Biomedicine, strong in pharmacology and Europe | Subscription | English | Once you have the references from all these sources, you need a system to manage them and remove duplicates. That is where choosing a [reference manager such as Mendeley or Zotero](/en/blog/mendeley-vs-zotero/) comes in: it centralizes all the results and helps you document the [screening of the articles](/en/blog/rayyan-vs-covidence/). Remember that this guide is one piece of the whole process. Read the [main guide on what a systematic review is and how to do one step by step](/en/blog/what-is-a-systematic-review/) to place the database search within the stages of the method.Bring the results from several databases into one place. In revisia you import, deduplicate and screen without switching tools. Create your free account.
## Frequently asked questions ### Is PubMed the same as MEDLINE? Not exactly. PubMed is the free interface that gives access to MEDLINE and to other additional records of biomedical literature. ### What is the Cochrane Library? A collection of evidence-focused databases that includes Cochrane systematic reviews and a register of clinical trials. ### Can I do a review with Google Scholar alone? It is not recommended as your only source. Its coverage is neither transparent nor reproducible, although it can work as a supplement. ### What is PubMed? PubMed is the free search engine of the US National Library of Medicine that gives access to MEDLINE, the reference bibliographic database in biomedicine. Its MeSH controlled vocabulary allows precise searches, and it is the most used source in health reviews because it is free and has very broad coverage. ### Scopus or Web of Science? In a systematic review you should use both rather than pick one, because they index different journals and only partly overlap. If you have access to both (both need an institutional subscription), search both. If you only have one, state it as a limitation in the protocol and strengthen the search with other databases. ### What is Dialnet? Dialnet is a large Spanish-language bibliographic portal run by the University of La Rioja, with multidisciplinary coverage and a strong presence in the humanities and social sciences. Access to the references is free, and it is especially useful for reviews, theses and dissertations in fields where much of the research is published in Spanish. ### How many databases should you search in a systematic review? There is no fixed number, but methods guidance recommends searching several complementary sources, usually at least three. For reviews of health interventions, the Cochrane Handbook suggests searching at least MEDLINE, Embase and CENTRAL, and adding subject or regional databases depending on the question. The key is to combine a multidisciplinary database, one specific to your field and one regional or in your language, and to document the strategy for each one.