Natyashastra
वस्तुशाखाख्यमित्येतद्गदितं त्वपरान्तकम् । यथा शाखा तथैवास्य प्रतिशाखा विधीयते ॥ २४१॥
This is called the Śākhā of the Vastu, and it is termed Aparāntaka. Just as there is a Śākhā, so too its Pratiśākhā is to be arranged.
english translation
vastuzAkhAkhyamityetadgaditaM tvaparAntakam । yathA zAkhA tathaivAsya pratizAkhA vidhIyate ॥ 241॥
hk transliteration by Sanscript