Phaladeepika
जीवे तु जीवात्मजनाथभशक- त्रिकोणगे पुत्रजनिर्भवेन्नृणाम् । अथान्यशास्त्रेण च जन्मकालतो निरूपयेत्सन्ततिलक्षणं बुधः ॥ २९॥
Men will generally have the birth of a son when Jupiter in the course of his orbit passes through a Rasi trine to the sign representing the Rasi or Amsa occupied by the planet owning the 5 th house reckoned from Jupiter. According to other treatises on the subject, one ought to investigate indications of progeny from the positions of planets at the birth time of the native.
english translation
jIve tu jIvAtmajanAthabhazaka- trikoNage putrajanirbhavennRNAm । athAnyazAstreNa ca janmakAlato nirUpayetsantatilakSaNaM budhaH ॥ 29॥
hk transliteration by Sanscript