Google search operator: inurl:
example: inurl:.int
link: [link to www.google.com (secure)]


List of Top Level Domains: [link to en.wikipedia.org]

Some more google search operators listed:
[link to libguides.mit.edu]

example: inurl:.gov intext:UFO filetype:(blank)
link: [link to www.google.com (secure)]

If you want to search for file type pdf, for example, do not add .pdf, just pdf, no period.