Here are links to search engines, links to search engine evaluation sites, links to web page evaluation sites and web page citation sites. Each service uses different commands and operates in different ways. Use more than one Search Engine.
Search engines vary in size, by method of searching, and by the way the search is performed.
Different search engines may yield different results. Review some of the literature that examines Search Engines. The Users' Guide to Web Searching. Search Engine Watch Robert, Harris. Internet Search Tips and Strategies.