Trikaya Sutra
The Three Kaya Sutra or Sūtra of the Three Bodies, (Skt. Trikāyasūtra, Tib. སྐུ་གསུམ་པའི་མདོ, ku sumpé do, Wyl. sku gsum pa'i mdo) contains an explanation of the three kayas: nirmanakaya, sambhogakaya and dharmakaya by the buddha, answering a question of the bodhisattva Kshitigarbha.