Mention by Panini
Vritta (वृत्त) is mentioned in Mahabharata (I.31.10), (I.35), (V.101.14)/(V.103)
Adi Parva, Mahabharata/Book I Chapter 31 mentions the names of Chief Nagas. Vritta (वृत्त) is mentioned in Mahabharata verse (I.31.10).... Kamvala, Ashwatara, Kaliyaka, Vritta, Samvartaka, Padma, Mahapadma....
Udyoga Parva/Mahabharata Book V Chapter 101 describes Bhogavati city and innumerable Nagas dwelling there It is ruled over by Vasuki, the king of the Nagas. Vritta (वृत्त) is mentioned in Mahabharata verse (V.101.14). .... Karavira, Pitharaka, Samvritta, Vritta, Pindara, Vilwapatra, Mushikada, Sirishaka, ....