In most databases you can combine keywords with Boolean operators. These are linking words with which you also can indicate the relationship between the search terms and the search result. The most common boolean operators are:
The operators AND and NOT limit the number of results from a search. The operator OR does the opposite; it increases the number of results.
You can also combine more than two search terms. Use brackets to indicate the priority. For example (Money OR inflation) AND banking.
To see how this works, take a look at The Boolean machine. Move your cursor over the operators AND, OR and NOT to see how they determine your search.
Besides the standard search bar on their homepage, most search engines and databases offer the "advanced search" option. This will make your search much more focused and effective. In advanced search screens you can combine various search techniques in one search. For instance combine or exclude search terms, search for publications published in a specific period or in a certain language.
Google , the most popular search engine, also has an advanced search screen. Watch the infoclip on Google Advanced Search.
Truncation (or wildcard symbols) can be used to broaden your search and include different spellings.
To do this, you shorten the search term to a word stem and, depending on which database you are using, you type either a question mark or asterisk behind the word stem. The results will then include various endings and spelling variations.
If you search using the term environ*, the results will include publications with ‘environment’, ‘environmental’ and ‘environmentally’ in the text and/or title.
You can also use a wildcard within a word. A question mark is used to replace a letter. This can be useful if you have doubts about the correct spelling of a word or if a word can be spelled in more ways.
For example, if you search using the term organi?ation, the results will include the British English spelling (organisation) as well as the American English spelling (organization).
If you search using the term labo?r, the results will include ‘labour’ as well as ‘labor’.
Note: The truncation symbol varies per database.
Consult the database's “help” or “search tips” page for details.
You can usually combine keywords using quotation marks to make phrases that search tools will try to match exactly. To search for a whole phrase put the words between quotation marks.
For example:
“European law”
Without the quotation marks you would get results for the individual words ‘European’ and ‘law’ as well, so this is a very useful way to target your search.
Please notice
If you search with "George Bush" you will not find any sources containing George W. Bush occurs, and if you search with "Childcare Maastricht", you will not find the search results that contain "childcare in Maastricht".
In these examples, searching with proximity operators is a suitable option.