Srimad Bhagavatam Canto 10, Chapter 84, Text 51

SB 10.84.51

ije ’nu-yajñam vidhina
prakrtair vaikrtair yajñair
Performing various kinds of Vedic sacrifice according to the proper regulations, Vasudeva worshiped the Lord of all sacrificial paraphernalia, mantras and rituals. He executed both primary and secondary sacrifices, offering oblations to the sacred fire and carrying out other aspects of sacrificial worship.
There are numerous kinds of Vedic fire sacrifice, each of which involves several elaborate rituals. The Brahmana portion of the Vedic sruti specifies the complete step-by-step procedure of only a few prototype sacrifices, such as the Jyotistoma and Darsa-purnamasa. These are called the prakrta, or original, yajñas; the details of other yajñas must be extrapolated from the patterns of these prakrta injunctions according to the strict rules of the Mimamsa-sastra. Since other yajñas are thus known by derivation from the prototype sacrifices, they are called vaikrta, or “changed.”
Srimad Bhagavatam Canto 10, Chapter 84, Text 50
Srimad Bhagavatam Canto 10, Chapter 84, Text 52