"Expression" - Use quotation marks to force an exact-match search.

Term1 AND Term2 - Search for simultaneous occurrences of Term1 and Term2 in the same text. E.g. José AND Maria.

Term1 OR Term2 - Search for occurrences of Term1, Term2 or both simultaneously. E.g. José OR Maria.

Term1 AND NOT Term2 - Search for occurrences of Term1 where Term2 does not occur. E.g. José AND NOT Maria.

(Term1 OR/AND NOT/AND Term2) OR/AND NOT/AND Term3 - Use parentheses to group terms or expressions, combining operators.
E.g. (José OR Maria) AND NOT "Antonio Miguel".

[NEAR((Term1, Term2), distance] - Define maximum number of words between two searched terms. E.g. [NEAR ((José, Maria), 10)].

[SIMILAR ("Term1")] - Search for words derived from the main term (plurals, tenses, gender variations, etc.).
E.g.: [SIMILAR("Association")] returns Associations. This operator may return false positives.