Brihat Parashara Hora Shastra
कृष्णपक्षे दिवा जन्म शुक्लपक्षे तथा निशि । तदा ह्यष्टोत्तरी चिन्त्या फलार्थञ्च विशेषतः ॥ २३॥
It will be advisable to adopt the Shodshottari, if the birth is in the day in Krishna Paksh (dark half of the month), or at night in Shukla Paksh (bright half).
english translation
kRSNapakSe divA janma zuklapakSe tathA nizi । tadA hyaSTottarI cintyA phalArthaJca vizeSataH ॥ 23॥
hk transliteration by Sanscript