Ooh, let me check and get back to you. I've only really read one run of stories, but I read a couple of trades that kind of overlapped? Like, one of them contained the stories from two of the others, so when I got to the others I was like, "Oh hey I already read this. :(" So I think they must have released them in several formats.

Anyway, I'll check what titles would give you the whole set of stories that I read, though! Possibly tomorrow if that's okay. :)