If you're looking for a definitive treatsie on zombies:
Since it's a game and requires one person to come up with stories, etc. it goes into a lot of detail abot a lot of things. The extra books cover lots of things regarding survival and hiding. And they've "fleshed out" some stuff on zombies. (Such as: how they see.) Specific to the ghouls of the setting, but lots of it couild apply to any zombie horde.