I put this together by slogging through the TSR archive descriptions:
Dragon Mountain - 8 sheets
From the Ashes - 5 sheets
Forgotten Realms Campaign Setting (both 2nd Ed versions) - 8 sheets
The Horde - 4 sheets
Ruins of Undermountain - 8 sheets
Ruins of Myth Drannor - 8 sheets
City of Splendors - 8 sheets
Al Qadim Land of Fate - 8 sheets
Al Qadim City of Delight - 8 sheets
These have "Monstrous Compendium booklets":
Night Below - 8 page booklet
Ruins of Zhentil Keep - 16 page booklet
Ruins of Undermountain II - 16 page booklet
Spellbound - 16 page booklet
City by the Silt Sea - 32 page booklet
The Nightmare Lands - 16 page booklet
These have separate monster books, but don't use Compendium to describe them:
Planescape Campaign Setting - 32 page booklet
Planes of Chaos - 32 page booklet
Planes of Law - 32 page booklet
Planes of Conflict - 32 page booklet
Rod of Seven Parts - 16 page booklet
Basically, the loose sheets seem to have appeared during the time from the launch of
2E (1989) until the publishing of the Monstrous Manual (1993), then they began with the Monstrous Compendium booklets, then later products (Planescape and Rod of Seven Parts specifically) don't reference the "Compendium" at all.
Realm of Terror did not specifically mention MC sheets in the description, however, it does have "24 full-color cardstock sheets, featuring haunted castles, horrid houses, and fiendish folk," so based on a 1990 release date, those fiendish folk sheets probably are MC sheets. I do not have this set to check specifically.