Upanishads
https://www.youtube.com/watch?v=_zLI8N7QDDc
Bhagawat Geeta
https://www.youtube.com/watch?v=PC0FW407FVs
Dhammapada
https://www.youtube.com/watch?v=MlyK_f-7pew
Chandogya Upanishad
https://www.youtube.com/watch?v=Jl0ezN3VRio
Maittreyana Upanishad
https://www.youtube.com/watch?v=fik-J71EMPA
https://archive.org/stream/yogadaranasutra00patagoog#page/n12/mode/2up
Naishkarma siddhi
http://www.exoticindiaart.com/book/details/naishkarmya-siddhi-of-sureshvara-NZB643/
Shankaracharya's commentary on the Upanishads
http://www.wisdomlib.org/
imp- katha (nachuiketa), mundaka, aittereya upanishad
https://www.youtube.com/watch?v=h-oHWn6czl8&t=2378s
brihadarnyaka Upanishad
https://www.youtube.com/watch?v=nHADPfvSIhQ