Ved Prakash Upaddhay
Upadhyay's most notable work was Kalki Avatar and Muhammad which was published in 1969 by Saraswat Vedanta Prakash Sangghha of Allahabad. The book is thought to be a partial adaption of the book Muhammad in World Scriptures (originally "Mithaq an-Nabiyeen", covenant of the prophets) by Ahmadiya scholar  Abdul Haq Vidyarthi. Originally written in Hindi language, in this book, he discussed his claim of the mention of Islamic prophet Muhammad as the Hindu avatar of Kalki in the Hindu scriptures (Kalki Purana, Vedas and Bhavishya Purana, etc.). After publication, the book became very popular in India. Bengali scholar Asitkumar Bandyopadhyay translated the book into Bengali language along with Upadhyay's other two books 'Narashangsa and the Antim Rishi" and "Religious Unity in the Light of the Vedas and the Puranas" and combined it in one edition in the same name. The book was later also translated into English by several translators entitling Muhammad in the Hindu scriptures and Muhammad in the Vedas and the Puranas, which gave the book immense popularity outside India. Besides popularity, the book was also criticized by many Hindu and Muslim bodies,