Brihat Parashara Hora Shastra
शुक्रांशके प्रजातस्य विचिन्त्या द्वादशोत्तरी । जन्मभात् पौष्णभं यावत् संख्या हि वसुतष्टिता ॥ २७॥
This Dasha system will be appropriate for one, whose Lagn is in the Navāńś of Śukr. Count from Janm Nakshatr to Revati. Divide this number by 8.
english translation
zukrAMzake prajAtasya vicintyA dvAdazottarI । janmabhAt pauSNabhaM yAvat saMkhyA hi vasutaSTitA ॥ 27॥
hk transliteration by Sanscript