OSE Encounter Activity Tables     Any original/official source
Monsters Of The Underworld     D&D 5e original/official source
Monster Manual     D&D 4e (no source link)
Monster Manual 2     D&D 4e (no source link)
D&D 2e Monstrous Manual     D&D 2e (no source link)
Monstrous Manual: Dragonlance     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)