Question: what are the different upanishads?
Answer: He summarizes the current Indological opinion to be that the Brhadaranyaka, Chandogya, Isha, Taittiriya, Aitareya, Kena, Katha, Mundaka, and Prasna Upanishads are all pre-Buddhist and pre-Jain, while Svetasvatara and Mandukya overlap with the earliest Buddhist and Jain literature.