sgra thal 'gyur rtsa ba'i rgyud
dra thal 'gyur root tantra. [IW]
This tantra explains how to reveal the level of nirmanakaya and how to accomplish the welfare of others through practices related to sound.
Note: The names, numbers and the tantras themselves in these lists may vary from teacher-to-teacher, tradition-to-tradition. Some call for 17, some call for 18, and some add still an additional tantra making the total 19. See also Seventeen Tantras of the Great Perfection and Eighteen Dzogchen Tantras for further reference.