Brihat Parashara Hora Shastra
भाग्याद्भाग्यगते शुक्रे तद्द्वये राहुसंयुते । एकत्रिंशास्त्रयस्त्रिंशे दारलाभं विनिर्दिशेत् ॥ ३३॥
Should Śukr be in Dharm from Dharm (i.e. in Putr Bhava), while Rahu is in one of the said Bhavas (i.e. in Putr/Dharm), marriage will take place during 31st, or 33rd year.
english translation
bhAgyAdbhAgyagate zukre taddvaye rAhusaMyute । ekatriMzAstrayastriMze dAralAbhaM vinirdizet ॥ 33॥
hk transliteration by Sanscript