Kurmapurana 2.14.74

Kūrmapurāṇa 2.14.74

mārgaśīrṣe tathā pauṣe māghamāse tathaiva ca /
tistro 'ṣṭakāḥ samākhyātā kṛṣṇapakṣetu sūribhiḥ //