When readers download a free book and like it, they tend to buy other books in the series. (angiesdiary.com)
I've bought low priced ebooks, and liked them enough to also buy other books from the author at a higher price. (jamigold.com)
When a reader starts reading a book because it is freely available on the internet, they may eventually end up buying other books of the authors they discover. (thecuriousreader.in)