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Boolean operators / proximity operator

Boolean operators are a tool for combining search terms. In the list below you find an overview of the operators. Pay attention to the influence of the selected interface language. Only capital-case letters may be used.

 

Dutch interface English interface French interface Outline Example
EN - AND AND ET - AND All terms entered must feature in reference(s) found communications AND telephone
OF - OR OR OU - OR At least one of the terms entered must feature in reference(s) found communications OR telephone
NIET- NOT NOT PAS - NOT The term following operator 'not' may not feature in reference(s) found communications NOT telephone
NABIJ - NEAR

 

 NEAR PRES - NEAR The terms preceding and following operator 'near' must both feature in references found, but there may be no more than 4 words between them. In which sequence terms feature does not matter. communications NEAR telephone

You can combine several operators in a single query. Because of the processing sequence (first NEAR, then AND, then NOT, then OR), you have to pay attention in your query to the sequence of the search terms and the used Boolean operators. It is recommended to make use of parentheses to indicate in which sequence processing must take place; the operator(s) inside parentheses are processed first.

For example, if you search via methods <Search> or <Advanced search> you could compile the following queries:
(vehicle OR vehicles OR automobile OR automobiles) AND ((suspension OR suspensions) NEAR (active OR semi-active))
or, using wildcards:
(vehicle$ OR automobile$) AND (suspension$ NEAR *active)  =  (vehicle$ OR automobile$) AND suspension$ NEAR *active


Please note

If you want to search for the title: The boy who did not talk any more and you enter this as search string the "NOT" is interpreted as a Boolean opertaor. Which means you might get an unexpected result. Because you actuelly searched for (The boy who did) not (talk any more).

You can (temporarily) suppress an operator by placing the whole search string between double quotes, i.e.:

"The boy who did not talk any more"

 

(More information on Phrase searching can be found here)