Additional search engines can be found on the Sogang University English links page
or on the NISS list of search engines

People have also recommended using the following for in-depth scholarly searches

while for finding plagiarism these have been commended: (a commercial site)

There is also a site that regularly copies and archives millions of URLs as they develop and disappear. It allows one to view sites that are no longer available, as well as earlier versions of still available sites.