Shiva Purana
तस्य पुत्रास्त्रयश्शिष्टाः दृढाश्वः श्रेष्ठ उच्यते ॥ हंसाश्वकपिलाश्वौ च कुमारौ तत्कनीयसौ॥ ३९॥
Three of his sons survived. The eldest of them was Dṛḍhāśva. Haṃsāśva and Kapilāśva were younger princes.
english translation
tasya putrAstrayazziSTAH dRDhAzvaH zreSTha ucyate ॥ haMsAzvakapilAzvau ca kumArau tatkanIyasau॥ 39॥
hk transliteration by Sanscript