These search engines search search engines. Use them to leverage the different indexing strategies. It may be more natural for you to think of what you want in the form of a natural language question than to try and connect keywords with boolean conjunctions. These will vary in efficiency depending how they are designed and how good you are at phrasing your question. NOT - Search will include entries that contain the first word but NOT the second.
Most search engines allow the use of quotes.
Evaluate the logic of your search string against the first few results.