Phaladeepika
निषेकलग्नाद्दिनपस्तृतीये राशौ यदा चारवशादुपैति । आधानलग्नादथवा त्रिकोणे रवौ यदा जन्म वदेन्नराणाम् ॥ ३१॥
The birth (of a child) may also take place when the Sun in his orbit passes through the third sign reckoned from the Rasi representing the Nisheka Lagna or transits a Rasi triangular to the (Adhana) Lagna
english translation
niSekalagnAddinapastRtIye rAzau yadA cAravazAdupaiti । AdhAnalagnAdathavA trikoNe ravau yadA janma vadennarANAm ॥ 31॥
hk transliteration by Sanscript