Srimad-Bhagavatam: Canto 9 - Chapter 1 - Verse 33
Sanskrit:
तेषां तु षट्प्रधानानां पृथुश्रवस आत्मज: ।धर्मो नामोशना तस्य हयमेधशतस्य याट् ॥ ३३ ॥
ITRANS:
teṣāṁ tu ṣaṭ pradhānānāṁpṛthuśravasa ātmajaḥdharmo nāmośanā tasyahayamedha-śatasya yāṭ
Translation:
Among these many sons, six were the foremost, such as Pṛthuśravā and Pṛthukīrti. The son of Pṛthuśravā was known as Dharma, and his son was known as Uśanā. Uśanā was the performer of one hundred horse sacrifices.