Saṃyutta Nikāya 43 1. Paṭhamavagga 4. Suññatasamādhisutta “Katamo ca, bhikkhave, asaṅkhatagāmimaggo? Suññato samādhi, animitto samādhi, appaṇihito samādhi—ayaṃ vuccati, bhikkhave, asaṅkhatagāmimaggo … pe …. Catutthaṃ.