Bhagavad Gita 10.28आयुधानामहं वज्रं धेनूनामस्मि कामधुक्।प्रजनश्चास्मि कन्दर्पः सर्पाणामस्मि वासुकिः ॥

Vajram the thunderbolt weapon made of the bones of Dadhichi an implement of warfare which can only be handled by Indra who has fininshed a hundred sacrifices.Kamadhuk The cow Kamadhenu of the great sage Vasishtha which yielded all the desired objects, also born of the ocean of milk.Kandarpa Cupid.Vasuki The Lord of hoodless or ordinary serpents.Sarpa (serpent) has only one head. Vasuki is yellowcoloured. Nagas have many heads. Ananta is firecoloured.Sridhara says that the Sarpa is poisonous and the Naga is nonpoisonous. Sri Ramanuja says that Sarpa has only one head and Naga has many heads.