X) button.author = miller. The = sign is actually a shorthand for contains. Searching for an exact match is possible using matches or ==.title = "image processing"and, or and nottitle|keywords = "image processing". To search for entries without the title or the keyword "image processing", type: title|keywords != "image processing" It is also possible to chain search expressions. In general, you can use and, or, not, and parentheses as intuitively expected:(author = miller or title|keywords = "image processing") and not author = brown and != author = bluenot ... contains ...)video and year == 1932 will search for entries with any field containing video and the field year being exactly 1932.anyfieldanyfield contains fruit: search for entries having one of its fields containing the word fruit. This is identical to just writing apple. It may be more useful as anyfield matches apple, where one field must be exactly apple for a match.anykeywordanykeyword matches apple: search for entries which have the word apple among its keywords. However, as this also matches pineapple, it may be more useful in searches of the type anykeyword matches apple, which will not match apples or pineapplekeycitationkey == miller2005: search for an entry whose citation key is miller2005entrytypeentrytype = thesis: search entries whose type (as displayed in the entrytype column) contains the word thesis (which would be phdthesis and mastersthesis). means: any character+ means: one or more timesauthor != .+ returns entries with empty or no author field.^ means: the beginning of a line[a-zA-Z] means: a through z or A through Z, inclusive (range)$ means: the end of a lineX{n} means: X, exactly n timesowner != ^[a-zA-Z]{3}$ returns empty and non-three-letter owners\b means: word boundary\B means: not a word boundarykeywords = \buv\b matches uv but not lluvia (it does match uv-b however)author = \bblack\b matches black but neither blackwell nor blackerauthor == black does not match john black, but author = \bblack\b does.author = \bblack\B matches blackwell and blacker, but not black.? means: none or one copy of the preceding character.{n,m} means: at least n, but not more than m copies of the preceding character.[ ] defines a character classtitle =neighbou?r matches neighbour and neighbor, and also neighbours and neighbors, and neighbouring and neighboring, etc.title = neighbou?rs?\b matches neighbour and neighbor, and also neighbours and neighbors, but neither neighbouring nor neighboring.author = s[aá]nchez matches sanchez and sánchez.abstract = model{1,2}ing matches modeling and modelling.abstract = modell?ing also matches modeling and modelling.year == 200[5-9]|201[0-1]​specifies the range of years 2005-2011 (200[5-9] specifies years 2005-2009;| means "or"; 201[0-1] specifies years 2010-2011).author = (John|Doe)matches entries written by either John or Doe.author = (John|Doe).+(John|Doe)matches entries written by both John or Doe.()[]{}\^-=$!|?*+.)( ) [ ] { } \ ^ - = $ ! | ? * + . ) is included in your search string, it has to be escaped with a backslash, such as \} for }.\\) have to be used: abstract = xori{\\c{c}}o matches xoriço.")" has a special meaning: it is used to group words into phrases for exact matches. So, if you search for a string that includes a double quotation, the double quotation character has to be replaced with the hexadecimal character 22 in ASCII table \x22.\", nor a double backslash \\" will work as an escape for ". Neither author = {\"o}quist with regular expression disabled, nor author = \{\\\"O\}quist with regular expression enabled, will find anything, even if the name {\"o}quist exists in the library.{\"o}quist as an author, you must input author = \{\\\x22o\}quist, with regular expressions enabled (Note: the \, {, _ and the } are escaped with a backslash; see above).