Pathfinder 2e Bestiary 3     Pathfinder original/official source
Kobold Press Tome Of Beasts     D&D 5e original/official source
D&D 2e Monstrous Manual     D&D 2e (no source link)
Monstrous Compendium: Al-Qadim     D&D 2e original/official source
Scruffy Grognard's Monstrous Manual     D&D 2e (no source link)