Limit Google Searches to Certain Types of Files
Contributed by AlexTheBeast 
Tagged: Google The “filetype” search option allows one to limit your google search to particular types of files.
Filetype allows you to limit which type of files to return in your search. These at least include the following formats:
DOC – Microsoft Word Files
PPT – PowerPoint Presentations
XLS – Excel Spreadsheets
HTML – Web Pages
HTM – Web Pages
PDF – Adobe Acrobat
For example to find powerpoint presentations on medicine one could search for:
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