(3 hrs) at IIT Varanasi, by Som Tyagi, in Hindi – Part1 https://www.youtube.com/watch?v=ZR6rXnOgClQ (1 hr) at IIT Varanasi, by Som Tyagi, in Hindi – Part2https://www.youtube.com/watch?v=XvbIrTBBM8U (2.5 hrs) at IIT Varanasi, by Som Tyagi, in Hindi – Part3https://www.youtube.com/watch?v=bLhpDZ5jMKM