Open Source Press is closing down by the end of the year. So this is your last chance to buy some of their books or ebooks from their website. You will get them from Amazon or buecher.de for a while longer, but eventually they will run out of stock too.
I own 13 of their printed books, and they are all of good quality. They offer ebooks too. Some (e)books are in English, but most are German.
Merry christmas and a happy new year.