Unless a roleplaying game book is primarily history-based, you don't find many source bibliographies anymore. It was more common fifteen or twenty years ago.
In my own personal experience, I even offered up bibliographical information (being a history major in university and all
) for an RPG sourcebook I wrote a chapter for, but it was dismissed almost out of hand by the editor. I was not pleased. But, in the end, it's the editors and developers who are the folks that usually decide these things. I know that most writers do the legwork and document it pretty thoroughly. Often, it's just a case of page space and relevance to the overall material, I suppose.
LQ
Drunken DM and the Speak with Dead spell: "No, I'm not the limed-over skeleton of the abbot, and no this special key in my boney fingers does not open the door to the secret treasury! ... Oh crap."