Māṇḍūkī Śikṣā 123

123

varṇā viṃśatirekaśca yeṣāṃ dvirbhāva iṣyate
prathamā madhyamā cāntyā yalavāḥ śaṣasāstathā

The speech sounds for which gemination is desired are twenty-one: / the first, the middle, and the last [of the classes], *y*, *l*, *v*, and likewise *ś*, *ṣ*, *s*.