Formulas, manuscripts and torn-out pages in The Witcher 3
Formulas are to Witcher 3 alchemy what diagrams are to the forge. The game calls them formulas, manuscript pages and torn-out pages depending on the tier, but each does the same job: it unlocks a potion, oil, bomb or decoction and lists what goes into it.
Superior versions take the enhanced version as an ingredient, so the ladders are worth reading upward. What each one consumes is on the Witcher 3 alchemy ingredients page.
Where Witcher 3 recipes come from
Most formulas in The Witcher 3 are bought. Herbalists and alchemists carry the common tiers, and the merchants page lists who stocks which recipe at what price.
The rest are quest rewards or loot from specific containers, which is why a formula can sit unavailable for a long stretch of a playthrough even with the ingredients already gathered.