Natyashastra
अतः परं प्रवक्ष्यामि ह्याश्रावणविधिक्रियाम् । बहिर्गीतविधौ सम्यगुत्पत्तिं कारणं तथा ॥ ३०॥
Now, I will explain the method of the recital, the correct origin, and the cause in the context of external singing.
english translation
ataH paraM pravakSyAmi hyAzrAvaNavidhikriyAm । bahirgItavidhau samyagutpattiM kAraNaM tathA ॥ 30॥
hk transliteration by Sanscript