Brihat Parashara Hora Shastra
यस्माद् यावतिथे राशौ खेटात् तद्भवनं द्विज । ततस्तावतिथं राशिं खेटारूढं प्रचक्षते ॥ ६॥
Padas for Grahas. Note the position of a Grah and see how many Rāśis away is its own Rāśi with reference to its position. Count so many Rāśis from the said own Rāśi and the resultant Rāśi will become the Arudh of the Grah.
english translation
yasmAd yAvatithe rAzau kheTAt tadbhavanaM dvija । tatastAvatithaM rAziM kheTArUDhaM pracakSate ॥ 6॥
hk transliteration by Sanscript