Brihat Jataka
चन्द्रज्ञजीवा: परिवर्तनीया: शुक्रारमन्दैरयने विलोमे ॥ द्रेष्काणभागे प्रथमे तु पूर्वो मासोऽनुपाताच्च तिथिर्विंकल्प्य: ॥ २६-३ ॥
The Moon, Mercury, and Jupiter are to be exchanged with Venus, Mars, and Saturn, respectively, when the ayana is reversed. In the first portion of the drekkana is the first month and tithi are to be calculated from the proportion.
english translation
candrajJajIvA: parivartanIyA: zukrAramandairayane vilome ॥ dreSkANabhAge prathame tu pUrvo mAso'nupAtAcca tithirviMkalpya: ॥ 26-3 ॥
hk transliteration by Sanscript