Databases are essentially organised collections of related information or data. Some databases consist of video’s, data, primary sources, images, or specialised information such as chemical reactions or genome sequences. Most databases, however, contain full-text articles or citations to articles published in academic journals, magazines and newspapers. Databases can be interdisciplinary (spanning several disciplines) or subject-specific (focusing on a particular discipline, such as history, psychology, or literature).

There's nothing wrong with using Google or another search engine to find information on the web. Sometimes it can even feel easier doing so because you can use natural language, such as "What is global warming?" or "When did the Apollo fly to the moon?". Just keep in mind that most of the information retrieved from the open web hasn't been evaluated. It could be inaccurate, biased, or it might not be current. 

Use Database Search to search for a specific database by name or browse the list to discover databases recommended for your subject. If you don't know which databases are commonly used in your discipline, check our subject guides for recommendations from your subject librarian. 

If time permits: use more than one database for a more thorough search. Each database covers a different range of journals.

1. Web of Science: citation and subject searching, mainly for the sciences
2. PubMed: citations from biomedical literature
3. Google Scholar: general search engine for scholarly literature
4. Nexis Uni: articles from Dutch local and national newspapers
5. JSTOR: full text journals
6. Proquest dissertations and theses: citations to dissertations from 1861 through the present
7. Academic Search Premier: general database for the humanities
8. Worldwide Political Science Abstracts: citations of articles in the political sciences
9. WorldCat: catalogue containing the holdings of over 70,000 libraries worldwide
10. PsycINFO: citations of articles in the behavioral and social sciences

Some databases contain the full-text PDF's of an article, other databases require you to click the GetIt@Leiden button to check if the UBL provides online access. If this is not the case search the Catalogue to find out if the library has a printed version available. Because not all articles available are indexed in the Catalogue don't forget to search for the title of the journal in which the article was published, not on the article title! 

Boolean operators

Boolean operators connect your search words together with AND, OR, and NOT to either narrow or broaden your set of results. Example:  Capital (title) AND Piketty (author) AND 2014 (year)

Use AND in a search to narrow your results and to tell the database that ALL search terms must be present in the resulting records. Example: cloning AND humans AND ethics. 

In many, but not all, databases, the AND is implied. For example, chocolate export fair trade is translated to: chocolate AND export AND fair AND trade. The words may appear individually throughout the resulting records. Use quotation marks to make your results more specific. For example: "fair trade". 

Use OR in a search to connect two or more similar concepts (synonyms) and to broaden your results, telling the database that ANY of your search terms can be present in the resulting records. Example: internet OR web OR online

Use NOT in a search to exclude words from your search or to narrow your search, telling the database to ignore concepts that may be implied by your search terms. Example: cloning NOT sheep

If you use a combination of AND and OR operators in a search, enclose the words to be "ORed" together in parentheses. For example: (ethic* OR moral*) AND (bioengineering OR cloning)

Truncation and wildcards

Truncation is a technique that broadens your search to include various word endings and spellings. To use truncation, enter the root of a word and put the truncation symbol at the end. The database will return results that include any ending of that root word. Truncation symbols may vary by database; common symbols include: *, !, ?, or #.  Examples: child* = child, children, childhood. 

Similar to truncation, wildcards substitute a symbol for one letter of a word. This is useful if a word is spelled in different ways, but still has the same meaning. Examples: wom!n = woman, women, speciali?ation = specialisation, specialization.

Subject headings and keywords

Keyword searching is how you typically search web search engines.  Think of important words or phrases and type them in to get results. The database will search within all fields of a record. 

Subject headings describe the content of each item in a database and are part of a 'controlled vocabulary' established by the publisher of the database. It is not always easy to know which subject headings are used in a database. Look to see if the database has an thesaurus to browse for subject headings or look for the subject heading in the record of a known item. 

It's worth checking the database help and guides. They will give you a better understanding of how to get the best results from a search.

If you’re looking for older information, databases may not always be the best source. For certain subject areas printed indexing and abstracting journals and bibliographies may still be the best, and only, means of tracing references to literature. Check the coverage information of a database under the i-icon or in the database itself.