Natyashastra
त्र्यस्रश्च चतुरस्रश्च षट्कलोऽष्टकलस्तथा । ध्रुवाणां तु भवेत्तालैस्तं च वक्ष्यामि तत्त्वतः ॥ ४०॥
The Tryasra and Caturasra Tālas, consisting respectively of six and eight Kalās, are to be used in the Dhruvās. I shall now explain this in detail.
english translation
tryasrazca caturasrazca SaTkalo'STakalastathA । dhruvANAM tu bhavettAlaistaM ca vakSyAmi tattvataH ॥ 40॥
hk transliteration by Sanscript