While I have used Dogpile satisfactorily for years, a recent comparison of online multi-engine searchers gave Northern Light the nod for relevance of returns. I use both, so I'll share both. Northern Light also has a private library of documents for a small fee. See also TopClick , a new, private and secure searcher which uses Google technology. AND, OR, NOT and the proper use of quotation marks will save hours online.
Details are always available at search sites.
In the meantime, amuse yourself looking at searches that others are making, as well as bone-headed language errors, with this link. While this serves no real purpose, it is entertaining. It's not really cheating, or even advanced, although that's what they call it. In contemporary searching this should be common sense. It's how to find what you really want, downloadable or printoutable.