Srimad-Bhagavatam: Canto 4 - Chapter 1 - Verse 2
इलायामपि भार्यायां वायो: पुत्र्यां महाबल: । पुत्रमुत्कलनामानं योषिद्रत्नमजीजनत् ॥ २ ॥
ilāyām api bhāryāyāṁvāyoḥ putryāṁ mahā-balaḥputram utkala-nāmānaṁyoṣid-ratnam ajījanat
The greatly powerful Dhruva Mahārāja had another wife, named Ilā, who was the daughter of the demigod Vāyu. By her he begot a son named Utkala and a very beautiful daughter.