The electronic book industry has been booming in Internet world after the creation of PDF format files. In computer, PDF format files can be opened and viewed easily like a book and print it out if you like!

If you are frequent Internet user, then you should know how tech-savvy people these days are in the skill of sourcing information on the Internet, it is not surprise to know that people would search and download for free information online; including free computer manuals, free textbook solution manuals, free recipes, repair manual ebooks, etc.

Some PDF search engines allow user to search for PDF files only, but the information is very limited. This is a great searching strategy you could learn as there will be more results in you did your searching for information in Google. But, how can you search for PDF format files only using Google?

Here is the secret trick you can use:

What you need to do is just type any keywords or phrases related with the PDF books you would like to search for, followed by this file format term ‘include filetype:pdf’ as shown below.

After that, the search result pages will show all the entries that are related to PDF format document available on the world wide web.