PDF Search Engine is another excellent tool for finding PDF documents and e-books on the internet. Just enter any keyword in the search field to find documents on that topics and the search results are also very good. Both these search engines response time is quite good, a quick search on any topic will show a good number of results.
Here are two excellent search engines for finding PDF document on the internet, which saves your time in searching and downloading for PDF documents. PDF Database is one such new tool which uses a unique system for searching PDF and doc files from all over the net. Its database is huge- more than 7million PDF and document file and still it growing.