Actually, 2nd edition only required 3 books to play. PHB, DMG and MM. All those other books were optional, and if you didn't want them being used, as the DM you have the right to say "This is what you can use to create your character, and nothing else unless it is appropriate for the campaign". Last thing to do is let the rule lawyers have their way going through one large collection of books. I have a number of books that I have decided are off-limits for characters, which starts with the PO books. My players aren't complaining, and if yours do, saying it's not fair, simply put the PHB, DMG, and MM are the only core books. Anything else is optional.
Actually, 2nd edition only required 3 books to play. PHB, DMG and MM. All those other books were optional, and if you didn't want them being used, as the DM you have the right to say "This is what you can use to create your character, and nothing else unless it is appropriate for the campaign". Last thing to do is let the rule lawyers have their way going through one large collection of books. I have a number of books that I have decided are off-limits for characters, which starts with the PO books. My players aren't complaining, and if yours do, saying it's not fair, simply put the PHB, DMG, and MM are the only core books. Anything else is optional.