How Many Devilman Manga Series Are There?

Just finished the first series (amazing), and I know there are more, but I've been pulling Google teeth just to find four more (Shin Devilman, Devilman Grimoire, Devil Lady, and Amon: The Darkside of The Devilman), and yet according to Wikipedia there are over thirty of them. For some odd reason I can't find any kind of list of these whatsoever. Even Go Nagai's Wiki only listed a few. I can only assume this means that the majority of them are terrible, but I'm still curious. Please help.