You’re using Bing and want to find documents, pictures, Mp3s linked by web pages. For instance you’re searching for a Powerpoint inside an expert  site. Or you’re searching all the web sites that contain mp3s. Here’s how to:

The Bing search engine has a very useful advanced search keyword, named contains: It keeps results focused on sites that have links to the file types that you specify. You can use it like this:
- to search for music in mp3 format, type music contains:mp3
- to search for all the pages that have a PDF on gardening, type gardening contain:pdf

Combine this search keyword with others to focus your search. Suppose you’re interested in Social Media report made by Forrester. Search social media site:forrester.com contains:pdf

Do you think this advanced search keyword is useful? How would you use it?