Bhagavatapurana 4.1.40

4.1.40

ūrjāyāṃ jajñire putrā vasiṣṭhasya parantapa /
citraketu-pradhānās te sapta brahmarṣayo 'malāḥ //

40-41. O Vanquisher of enemies (Vidura), the sons of Vasishṭha by Ūrja (Arundhati) were Chitraketu and others who became the seven sages of untainted nature; these were called Chitrakētu, Surochis, Virajas, Mitra, Ulbana, Vasubhridyāna and Dyumat; and Vasishṭha had also other sons, Sakti and others, (who were born of another wife).