Natyashastra
प्रथमस्त्वष्टकलः स्याद्द्वादशकलिकौ तथापरौ ज्ञेयौ । अन्त्यश्च सन्निपातो मध्यस्यासारितस्योक्तः ॥ १६०॥
The first section should consist of eight Kalās, the next two of twelve Kalās each, and the last should end with a Sannipāta — this is said to be the structure of the medium Āsārita.
english translation
prathamastvaSTakalaH syAddvAdazakalikau tathAparau jJeyau । antyazca sannipAto madhyasyAsAritasyoktaH ॥ 160॥
hk transliteration by Sanscript