Siirry pääsisältöön

Guide to Information Seeking: Retrieval techniques

Retrieval techniques

Boolean logic allows you to combine search terms. Boolean operators are AND, OR and NOT. Most of the databases have advanced search where boolean operators are installed between search fields so you do not have to write the operators yourself.


Boolen operaattori AND

AND narrows down your search results

AND operator tells the database that all your search terms must occur in the result. This reduces the number of search results. For example, when searching for materials that discuss both renewable energy and attitudes towards it, you combine the search terms with AND operator: renewable energy AND attitudes


Boolean Operator OROR broadens your search results

OR operator tells the database that at least one of the search words, but not necessarily all, must occur in the results. This increases the number of search results by giving the database alternatives. You can use OR to search for synonyms, for example green OR renewable OR sustainable. You can also combine related terms, for example wind power OR solar power, acronyms or broader and narrower terms.


Boolen operaattori NOT

NOT excludes all the records that include the chosen search term

NOT operator tells the database that the chosen search term cannot be included in the search results. This reduces the number of search results. Be careful when using NOT as it might leave out some relevant results. Example: renewable energy NOT wind power


See video on how to use Boolean operators to improve your search results.

Video:  BethelUnivLibrary

It's possible to combine several Boolean operators. You can think of alternate terms for all of your search words, combine them with OR, and then combine these groups with AND. You get the widest possible search result by combining regular words (key words) with subject terms from thesauri.

If you write the operators yourself, use parentheses to specify the order in which the search terms are interpreted. Terms within parentheses are read first. For example: (green OR renewable OR sustainable) AND (energy OR power) AND (attitudes OR views). Without the parentheses most databases will read terms combined by AND first, which will change the search result.

See how to combine search terms in Finna advanced search.

Use term truncation or wildcards to include various word endings and spellings in the search result. Truncation or wildcard is marked with an asterisk (*) or a question mark (?) depending on the database you are using. Wildcard is useful for example when using search terms in English, as British and American English spellings vary, like in words organization vs. organisation, analyze vs. analyse etc.

Please check in the database instructions that you are using the right symbol. Many databases use automatic truncation and truncation symbols are not needed.

In Turku UAS Finna, the ? symbol substitutes one letter and * symbol substitutes none, one or more letters of the search term.

Example from Finna:
- using the search term licen?e (wildcard) includes both licence and licence in the search result
using the search term licenc* (truncation) includes licence, licences and licencing in the search result

Use phrase search if you want to search for an exact phrase (two or more words in a specific order). Search engines search phrases marked with quotation marks in the order and form that are given.

Use quotation marks around the words for example "social media" and "management models".

Many databases offer phrase search functions such as "this exact phrase". 

Narrow down your search with different ways:

  • year: publishing year. Narrow down your search and browse your search results with date, descending or ascending.
  • language: narrow down your search with publishing language.
  • content type: journal article, book article, book etc. You can also narrow down your search result by selecting only peer reviewed or scholarly articles/journals.
  • full text: publication is available online in electronic form.

Google Search

Google, too, is a database, and like other databases it understands Boolean logic. You can improve your search results by using the retrieval techniques discussed above, such as Boolean operators and quotation marks. Please note that with Google you should use a minus sign instead of NOT to exclude a word, for example solar power -wind power

You can also use Google's advanced search option to improve your results. Advanced search can be found in Settings > Advanced search (see bottom of the page).












Advanced search has search fields where operators are automatically added between search words, so you do not have to write the operators yourself:

Advanced search also offers many options for narrowing your search, such as searching a specific site or domain, or filtering results by usage rights.

Information retrieval checklist

Not enough search results Too many search results
  • Use more common search terms. Search using broader concepts, for example climate protection -> environmental protection
  • Use more precise search terms. Think of core concepts for your topic. Search using narrower concepts, for example wastes -> packaging waste
  •  Check the truncation. Does the search result include alternate spelling?
  • Check the truncation. Truncating the search term incorrectly can result in extra results
  • Do a basic search and search all fields
  • Use advanced search and limit the search to title for example
  • Use keywords instead of subject terms
  • Use controlled subject terms instead of keywords. See the database's thesaurus for which subject terms you should use
  • Add parallel search terms, synonyms or acronyms with OR operator
  • Remove parallel search terms combined by OR operators
  • Remove AND and NOT operators. They limit your search result. Especially NOT can leave out good results
  • Use AND operator to include terms in your results and NOT operator to exclude terms you don't want in your results
  • Remove options that narrow down your results, especially full text only limitation
  • Narrow down your search with different options: language, country, date, content type, location
  • Are you using the right database?

About this guide

This guide aims to support Turku UAS students and staff in searching information. It is a major part of the study material in the Information Skills Online Course.

Additional help

Finding an interesting publication can help you come up with ideas for new searches:

  • Click open the record in your search result list and study it carefully. Which subject terms have been used to describe the contents? Subject terms help you think up more search terms and broaden or narrow your search.
  • Check if the author has written something else on the same topic.
  • Look at the bibliographies of the publications you have found. Works cited might prove useful to you too.

Do you need help?

Contact Library at the Turku University of Applied Sciences by email

We are happy to help you!

Usage rights of the guide

Creative Commons -lisenssi
This publication has been licensed with the Creative Commons Attribution 4.0 International license