Shiva Purana
मासस्त्रिंशदहोरात्रैर्दिव्यो मानुषवत्स्मृतः ॥ संवत्सरो ऽपि देवानां मासैर्द्वादशभिस्तथा ॥ ९ ॥
The divine month like the human month constitutes thirty days. The year of the gods constitutes twelve months.
english translation
mAsastriMzadahorAtrairdivyo mAnuSavatsmRtaH ॥ saMvatsaro 'pi devAnAM mAsairdvAdazabhistathA ॥ 9 ॥
hk transliteration by Sanscript