Google Scholar offers several features of interest to scholars. You will want to use Google Scholar, in combination with library databases, to cast the widest net to find sources. For example, library databases often do not include conference proceedings articles. Google Scholar will often find conference articles.
Google Books includes searchable text of books and magazine articles. Some books are available full-text if they are out of copyright or if the publishers has given permission to Google to offer the text. Most books are not available online. But, Google Books is a great search to find topics and keywords in books. Google links to library collections that include books found in the service.
A useful browser feature is to search for text on a webpage - use Control-F (PC) or Command-F (Mac) and search for your word.