Natyashastra
विधिर्यश्चतुरश्रस्य भित्तिस्तम्भसमाश्रयः । स तु सर्वः प्रयोक्तव्यस्त्र्यश्रस्यापि प्रयोक्तृभिः ॥ १०४॥
The procedure for the four-cornered structure (chaturashra) with walls and columns should be followed. The same procedure should also be used by the practitioners for the triangular (trishra) structure.
english translation
vidhiryazcaturazrasya bhittistambhasamAzrayaH । sa tu sarvaH prayoktavyastryazrasyApi prayoktRbhiH ॥ 104॥
hk transliteration by Sanscript