||You can indicate with + that a word has to appear in the keywords of the page ("+Otto +engine" gives results where Otto and engine appear as a keyword)
||With - you can indicate that a word mustn't be in the keywords ("+Otto -clown" gives results where Otto but not clown appear in the keywords)
||A space before a keyword indicates that the following can be in the keywords but it's not necessary ("Otto engine" gives results where Otto or engine appear in the keywords).
||Finally you can indicate with quotation-marks that the text inside two quotation-marks has to be in the keywords. If you want to find keywords with quotation-marks inside the keyword, you can add a backslash (\) before the quotation mark. ("engine +"August Otto" +combustion" gives results, where engine, combustion and August Otto appear in the keywords).