AND means that all words must appear in the search result
You use the AND relationship to link two (or more) different subjects.
The search result is limited, smaller than the one-word search.
For example: you are looking for information about the relationship between obesity and nutrition in canteens. Search terms and relation: obesity AND canteens
OR
OR means that at least one of the words appears in the search result
the OR relation is used for (almost) synonyms, plural/singular, different spellings
The search result is increased, extended compared to the one-word search
Example: in addition to canteens, you also want to search school canteens. Search terms and relationship: canteens OR school canteens
NOT
You can use the NOT relationship to exclude a certain word/subject
The search result is narrowed down
Example: you want information about canteens in schools, but not about canteens in primary schools. Search terms and relationship: schools NOT primary schools
Tips!
Type AND/OR/NOT with capital letters
Sometimes you can also use Boolean operators in Dutch, then it is: EN/OF/NIET
If you combine several Boolean operators, put the OR terms between brackets. Example: (canteens OR school canteens) AND obesity. If you do not use brackets here, the AND command only works for school canteens AND obesity
If you put your search terms in parentheses or quotes, these terms get high priority in the search.