Matsyapurana 17.8

17.8

śrāvaṇasyāṣṭamī kṛṣṇā tathāṣāḍhī ca pūrṇimā
kārttikī phālgunī caitrī jyeṣṭhapañcadaśī sitā
manvantarādayaś caitā dattasyākṣayyakārikāḥ //

The ninth day of the bright fortnight of the month Aśvin, the twelvth tithi of the month Kârtika, the third lunar day of the month Chaitra, the third lunar tithi of Bhâdra, the Amâvasya of the month Phâlguna, the 11th lunar tithi of the month Pauṣa, the 10th lunar tithi of the month Âsâḍha, the 7th tithi of the month Mâgha, the 8th of dark fortnight in the month Srâvana, the full moon days of the months Âsaḍha, the full moon days of of the months Kartika, Phalguna, Chaitra and Jyeṣṭha, these fourteen days are anniversary days of the beginning of fourteen Manvantaras respectively. These are the periods in which, if the Śrâddha is performed, it gives unbounded satisfaction to the Piṭris and brings exhaustless merit to the worshipper.--6-8.