Matsyapurana 5.23

5.23

dhruvasya kālaḥ putrastu varcāḥ somādajāyata
draviṇo havyavāhaśca dharaputrāv ubhau smṛtau //

The four sons of Âpa are Sânta, Danda, Sâmva, and Maṇivakra. They became the protectors of sacrifical rites.—22. Dhruva became the father of Kâla, Sôm of Varchâ, Dhara of Draviṇa and Havyavâha. Draviṇa and Havyavâha were born of Kalyânî, and Manoharâ, the daughter of Hari, was the mother of Prâṇa, Ramaṇa, Śisra.—23-24.