Natyashastra
षट्कलोऽष्टकलश्चैव तालो ह्यस्मात्प्रवर्तते । द्विप्रकारः पुनश्चायं निःशब्दः शब्दवांस्तथा ॥ १६॥
From this (Sannipātādi), Tālas of six and eight Kalās arise. This Tāla again is of two kinds — one without sound (silent) and the other with sound.
english translation
SaTkalo'STakalazcaiva tAlo hyasmAtpravartate । dviprakAraH punazcAyaM niHzabdaH zabdavAMstathA ॥ 16॥
hk transliteration by Sanscript