Electronic IT-books at a free price on Books.ru

On the site Books.ru is the action " E-books at your price! ". Books are mainly IT areas. Quote from the site:
Three days, from December 30 to January 1, 2015 inclusive, we offer about 1250 e-books at a free price. This means that you can pay for books as much as you see fit. We increased the number of books compared to previous promotions, adding about 50 new books.
Link to the list of books itself - http://www.books.ru/aktsiya-2015-4021718/
You must register, but after that you can set your price for any book from the list (minimum - 1 ruble). I want to note that in the beginning there are really new books, then old ones (which participated in similar events in the past), then with rare specks they are again interesting and new - so be careful!