I tend to divide 1E AD&D into 3 eras:
Early AD&D is roughly 1977-80 and consists generally of the Monster Manual, Players Handbook, Dungeon Masters Guide, Deities & Demigods, World of Greyhawk folio, early modules (A1, C1-2, D1-3, G1-3, Q1, S1-3, T1) and accessories (The Rogues Gallery, etc.)...