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Information Skills Toolbox

Search Methods

Use search methods to specify your search results. Here are a few examples of methods you can apply:
Pearl growing:
Pear growing is using one information item (like a search term/keyword or citation) to find more information. This method involves searching in Library catalogues or databases using search terms/keywords.Look through the initial search results and try to find better search terms, then  search further using the new terms.
Snowballing is tracking down references (or citations) in documents. The snowball method is a way of finding literature by using a key document on your subject as a starting point. Consult the bibliography in the key document (book or journal article) to find other relevant titles on your subject. You then look in the bibliographies of these new publications to find yet more relevant titles.

The advantage of the snowball method is that you can find a lot of literature about a subject quickly and relatively easily. The disadvantage of this method is that you are searching retrospectively, so each source you find will be older than the previous one (especially in the case of books).

Citation search

Many of the publications you find will contain relevant bibliographies. The disadvantage is that these titles always pre-date the publication in which they are mentioned. Citation searches reverse this process: who has cited the publication you have found? In this way you will find recent literature.


Search Techniques

Boolean operators

You can use the boolean search operators AND, OR and NOT to combine search terms

The operators AND and NOT limit the number of results from a search. The operator OR increases the number of results.


  •  Cycling AND traveling : combines these two words
  •  Cycling OR traveling : searches for the words cycling OR traveling. This search will produce more results. (Tip: the operator “OR” can also be used to include different spellings and translations or synonyms in the search).
  •  Cycling  NOT "mountain biking" : searches for the word cycling and excludes the term mountain biking.

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.

You can also combine more than two search terms. Use brackets to indicate the priority. For example (Leisure OR tourism) AND sustainability.

Phrase search

Phrase search is searching for an exact combination of words (exact phrase). You can put combinations of words or whole sentences in between quotation marks, such as  "mountain biking" in the example above. Such a combination will then occur exactly as quoted in the documents found. This is very useful if you are searching for a name, a compound or a title.

Truncation (or wildcard symbols)

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 after the word stem. The results will then include various endings and spellings.

If you search for environ*, the results will include publications with ‘environment’, ‘environmental’ and ‘environmentally’ in the text and/or title.  
A question mark replaces a letter in a word; the results include British as well as American spellings. For example, if you search for 
organi?ation, the results will include the British English spelling (organisation) as well as the American English spelling (organization).

In the videos on the left hand side you can find more examples of these search techniques.