The books used to source the monsters in the Index are as follows:
- L1 - Labyrinth Lord
- L2 - Labyrinth Lord Advanced Edition Companion
- M1 - AD&D 1st Edition Monster Manual
- M2 - AD&D 1st Edition Monster Manual 2
- FF - AD&D 1st Edition Fiend Folio
- CC - D&D Creature Catalogue
- ToH - Swords & Wizardry Tome of Horrors Complete