Natyashastra
द्विसङ्ख्याते निवृत्तिस्तु कार्याद्यस्यार्धयोगतः । द्विसङ्ख्यातार्धयोगेन त्रिसङ्ख्यातेऽपि चेष्यते ॥ ११७॥
In the double Āsārita, the repetition (nivṛtti) should be made by adding half ॥ a gaṇa॥ to the original form; and in the triple Āsārita too, it is to be performed by adding half ॥ a gaṇa॥ to the double one.
english translation
dvisaGkhyAte nivRttistu kAryAdyasyArdhayogataH । dvisaGkhyAtArdhayogena trisaGkhyAte'pi ceSyate ॥ 117॥
hk transliteration by Sanscript