Your success with a search has a lot to do with your expectations, what they make you consider as implausible and what you see as hope for success.
Engineers usually have it easier than, say, students of English.
But although engineering topics are usually better defined, you are usually alone with your computer. For now at least your local reference librarian is not available over an online chat session, but relevant collections and tabulations by librarians may be available online. If your search terms are quite specific try your luck with some of the major search engines. Their results can differ markedly, so do try several of these tools. At its best, successful searching on the Web involves the fortuitous intersection of hunches and connections, backdoors to information.