Phaladeepika
पञ्चाघ्नाच्छशिनः फुटादिशुहतं भानुस्फुटं शोधये- न्नीत्वा तत्र तिथिं सिते शुभतिथौ पुत्रोऽस्त्ययत्नादपि । कृष्णे नास्ति सुतस्तिथेर्बलवशाद्ब्रूयाद्द्वंयोः पक्षयोः दर्शे च्छिद्रतिथौ च विष्टिकरणे न स्यात् स्थिराख्ये सुतः ॥ १५॥
Substract five times the figures for the Sun from five times the figures for the Moon. If the Tithi represented by the result be an auspicion one in the bright half of a month, progeny is assured to the native (even) without much exertion. But if it be one of the dark half of the month, there is no such possibility. It is by a close examination of the strength of the Tithi-whether it is auspicious or otherwise-in both the Pakshas-bright and dark that one has to divine the possibility of the native being blessed with issue. During an amavasya (Amavasya), a chidra (Chidra) Tithi, the visti (Vishti) Karana or any one of the sthirakarana (Stthira-karanas), there will be no issue at all.
english translation
paJcAghnAcchazinaH phuTAdizuhataM bhAnusphuTaM zodhaye- nnItvA tatra tithiM site zubhatithau putro'styayatnAdapi । kRSNe nAsti sutastitherbalavazAdbrUyAddvaMyoH pakSayoH darze cchidratithau ca viSTikaraNe na syAt sthirAkhye sutaH ॥ 15॥
hk transliteration by Sanscript