Phaladeepika
उदयर्क्षशस्फुटतुल्यांशे निवसन् पूर्णं फलमाधत्ते शनिवद्राहुः कुजवत्केतुः फलदाता स्यादिह सम्प्रोक्तः ॥ ३४॥
A planet produces the full effact of the Bhava in which it is when its distance (in Navamsas, degree etc,) from the commencement of the Rasi occupied is equal to that traversed by the Lagna-point in the Lagna Rasi. It is declared by the authorities that Rahu is simlar to Saturn and Ketu to Mars in giving effects.
english translation
udayarkSazasphuTatulyAMze nivasan pUrNaM phalamAdhatte zanivadrAhuH kujavatketuH phaladAtA syAdiha samproktaH ॥ 34॥
hk transliteration by Sanscript