Denis Zaletaev (mexus)
Google
A little bit overhyped place but it's still okay. More expensive than its competitors and they don't bother separating science-based literature from someone fraud (like you can find "alternative history" books at the same place as the real history books). The store mostly aims at profit by any means, so you'll find all kinds of weird stuff there.
Having said that, if you know what you are looking for it's might be a good place then: they have electronic catalogues every here and there so you don't have to browse all the shelves on your own, and they have a very, very big selection on various topics.