iBooks is a popular app to read the ebooks on your iPad. But iBooks app only supports epub filetype and you have to convert the ebooks into epub to read them on iPad.
epub files can be dragged and dropped into iTunes to sync with iPad and you can save a lot time which you spend during conversion. However, it is not easy to find the ebooks for iBooks by using google search engine with simple queries.
Here are some special queries to easily find the ebooks in epub format.
You can also add the title and/or author of the ebook in your search by using this query: