Pathfinder 1e Bestiary 1     Pathfinder original/official source
Pathfinder 1e Bestiary 2     Pathfinder original/official source
Pathfinder 2e Bestiary 1     Pathfinder original/official source
Monster Manual 2     D&D 4e (no source link)
Scruffy Grognard's Monstrous Manual     D&D 2e (no source link)