OSE Encounter Activity Tables     Any original/official source
Monsters Of The Underworld     D&D 5e original/official source
D&D 2e Monstrous Manual     D&D 2e (no source link)
Scruffy Grognard's Monstrous Manual     D&D 2e (no source link)
AD&D Monster Manual     AD&D 1e (no source link)
Dragonlance Bestiary     SAGA (no source link)
Lairs And Encounters     Adventurer, Conqueror, King (no source link)