Anandakanda 1.21.24

1.21.24

bahiḥ ṣoḍaśapatreṣu vilikhetṣoḍaśa svarān /
dvātriṃśaddalake kādisāntadvātriṃśadakṣarān //

Outside, on sixteen petals, one should write the sixteen vowels; / on thirty-two petals, the thirty-two consonants from ka to sa;