Use quotation marks to search for a phrase. Searching for rock and roll will return documents with any of the words rock , and or roll . Try different arrangements of key words eg. This is a combination of a phrase and a single word. Remember though, that in North America they use native rather than indigenous - think of how your key words will be written on the document.
Some search engines are case sensitive.
Most search engines will match both upper and lower case if lower case letter are entered, but only upper case if upper case letters are entered. Most search engines will match part or whole of a word - eg. sing will retrieve singer, single, singe etc. Most search engines will search for documents with any of the words you enter - eg. Documents with both of the words will appear earlier on in the results. Results are returned in order of relevance.