The Monsters Know What They're Doing     Dungeons And Dragons original/official source
OSE Encounter Activity Tables     Any original/official source
Pathfinder 1e Bestiary 1     Pathfinder original/official source
Pathfinder 2e Bestiary 1     Pathfinder original/official source
Undead Revisited     Pathfinder original/official source
Monster Manual     D&D 5e original/official source
Flee, Mortals     D&D 5e (no source link)
Monster Ecology Anthology     D&D 5e (no source link)
Monster Manual     D&D 4e (no source link)
Scruffy Grognard's Monstrous Manual     D&D 2e (no source link)
The Monster Overhaul     OSR (no source link)
Abnormal Undead     Any original/official source