Angry Golem (web)     D&D 5e original/official source
Pathfinder 1e Bestiary 1     Pathfinder original/official source
Mythic Monster Manual v1     Pathfinder original/official source
Monster Classes: Sand And Spirit     Pathfinder 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)