Search any book on any topic using the following three sites. Key in your keyword in Google Search box and then select any of the three websites for Book Search.. And then wait and see the magic! Yes, it's free!
Google

If you are looking for books on the IITJEE, GATE, CAT, GMAT, GRE, SAT, TOEFL iBT, Computers/Technology, or any fictional/non-fictional book, then you have come to the right place!! Just go ahead and try out!