Keyword searches work on the principal of specific indexes that are created by searching all of the contents of certain Web sites. If everything you have tried fails, your about ready to throw the computer out of your window, you have one of two choices left. A Complex search or a Mobile search. A Complex search consists of really getting into the nitty-gritty and getting so specific with the search engine that Albert Einstein would turn in his grave. A Mobile search is actually the last resort of searches.
Every search engine have different characteristics.
The best thing to do is to explore each one and learn for yourself which one of them your comfortable in using and more importantly, which one of them retrieves the best and closest result to your query. It'll tell the search engine that you want a more specific search to be made. Remember, the key to a successful search is to be patient and very specific.