Surya Siddhanta
महत्त्वाच् छीघ्रपरिधेः सप्तमे भृगुभूसुतौ। अष्टमे जीवशशैजौ नवमे तु शनैश्चरः॥
Venus and Mars (leave their retrogression about the same time) when (their 2nd Kendra) is equal to 7 signs, on account of the greatness (of the rectified dimension) of their 2nd epicycle: so Jupiter and Mercury (leave their retrogression) when (their 2nd Kendra)=8 signs, and Saturn leaves its retrogression when (its 2nd Kendra)=9 signs.
english translation
mahattvAc chIghraparidheH saptame bhRgubhUsutau। aSTame jIvazazaijau navame tu zanaizcaraH॥
hk transliteration by Sanscript