Revākhaṇḍa of the Skandapurāṇa manuscripts (RKS) 88.8

88.8

kārttikyāṃ ca tathā mādhyāṃ vaiśākhyāṃ ca tṛtīyayā /
caitryāṃ caiva tathā ṣaṣṭhyāṃ prauṣṭhapadyāṃ tathaiva ca //

likewise on the full moon of Kārttika, the full moon of Māgha, and the third of Vaiśākha,
and on the full moon of Caitra, and likewise the sixth, and on the full moon of Prauṣṭhapada;