From BrWiki
The Dungeon Master's Guide or DMG is a book published by Wizards of the Coast. It is a key resource for any player of Dungeons & Dragons. It contains the rules for how the Dungeon Master can work with the players and set up and control scenarios in the game. Different editions were produced for each version of D&D. Some versions have additional volumes (e.g. the DMG II).
The rules in the BRCS expect that any Birthright Dungeon Master has access to the D&D Dungeon Master's Guide. It does not expect access to the DMG II or any additional voulmes.