Narada Purana (Jyotisha Selections) · by Vyasa
Chapter 6 · Calendar, Muhurta Elements
कालमानं मुहूर्ताङ्गानि च
मृगाच्छिशिरवसंतश्च ग्रीष्माः स्युश्चोत्तरायणे ।वर्षा शरच्च हेमंतः कर्काद्वै दक्षिणायने ॥ १२८ ॥
In the full Narada Purana (Purva Bhaga) this is chapter 56, verse 128.
From Capricorn come Shishira, Vasanta and Grishma, in the northward course. From Cancer come Varsha, Sharad and Hemanta, in the southward course.
Simple meaning: Three seasons fall in the Sun's northward half and three in the southward half.
चांद्रो दर्शावधिः सौरः संक्रांत्या सावनो दिनैः ।
A month can be counted by the Moon, by the Sun, by thirty days, or by the Moon's round of the stars.
मधुश्च माधवः शुक्रः शुचिश्चाथ नभस्ततः ।
These are the first ten names of the twelve lunar months.
तपास्तपस्य क्रमशश्चैत्रादीनां समाह्वयाः ।
Tapas and Tapasya are the last two month names. The rest of the sentence runs into the next verse.