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Searching Information: Search techniques

The information search process: search techniques

Choosing search techniques

Once you have found useful information sources for your subject and determined which search terms to use, you have to consider how to make your information search more effective by using various techniques.

Various information search techniques

Boolean operators

Boolean operators AND, OR, and NOT can be used to combine search terms. They are included in many databases. 

Boolen operaattori AND

The AND operator searches for documents including ALL search terms given. If you want to find research publications on attitudes towards renewable energy, search: renewable energy AND attitudes


Boolean Operator OR
The OR operator searches for documents including one or several search terms given. Usually, OR is used to combine synonyms: Green OR renewable OR sustainable


Boolen operaattori NOT
The NOT operator excludes references to the search term given. Be careful when using the NOT operator, there is a risk of missing relevant references!


Combining multiple operators

You can also use several Boolean operators in the same search. The priority of the Boolean operators is NOT, AND, OR. The search engine will first combine the search terms enclosing NOT, then the search terms enclosing AND and finally the search terms enclosing OR.  The automatic search order can be changed by using parentheses (). The search engine will first read the search statement within the parentheses, then combine the parentheses with each other. The parentheses can also include phrases.

You are searching for literature on the politics of renewable energy. The search:
("renewable natural resources" OR "renewable energy sources" OR bioeconomy) AND (“energy policy” OR “environment policy”)  
will return hits including at least one of the terms "renewable natural resources", "renewable energy sources" or "bioeconomy" and also one of the terms "energy policy" or "environment policy".


As a general rule, always use parentheses when including several operators in the same search statement.


By truncating the search term, you can search various word endings and spellings. The most common truncation symbols are, depending on the database, * or ?. Check the database instructions for the correct symbol.

sourc* -> source, sources, sourcing
journalis? -> journalist, journalism

Many databases (ProQuest, for example) use automatic truncation, which means that the search engine searches for different word endings automatically. However, in the library databases (Tria, Melinda) you will have to truncate the search term.

Wildcard symbols

By using wildcard symbols, you can replace one or several characters/letters in the search term. The wildcard symbol is convenient for search terms that can be spelled in several ways. Wildcard symbols vary from database to database, check the instructions.

organi?ation -> organisation, organization

Phrase searching

Phrase searching is the most convenient way to search for two or more words as an exact phrase, by using quotation marks.

"renewable energy"
"human resource management"

Subject terms

Subject terms are used to describe the contents of database resources. Databases usually include a thesaurus or list of subject terms.

The use of subject terms makes the information search process easier - if you choose your subject term well, you will probably find many useful resources in one search, while you will have to do several searches using keyword search. When your search generates a good result, check the subject terms of the document and use them to do a new search.

Finnish thesauri:

An example on how to combine different search techniques

In this example, Boolean operators are combined with truncation of search terms. Choose a precise search term that covers the subject.

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