Pathfinder 1e Bestiary 2     Pathfinder original/official source
Dragon Magazine     D&D 2e/3e (no source link)
D&D 2e Monstrous Manual     D&D 2e original/official source
Scruffy Grognard's Monstrous Manual     D&D 2e (no source link)
Role Aids: Giants     AD&D 1e (no source link)