From Rangjung Yeshe Wiki - Dharma Dictionnary
Guru Vidyadhara (bla ma rig 'dzin).
- A deity and set of scriptures belonging to the Nine Sadhana Sections. Often the Guru Vidyadhara and the eight herukas in the Eight Sadhana Teachings form a single mandala with nine groups of deities. The chief existing scripture for the teachings on Guru Vidyadhara is called the Root Tantra of the Assemblage of Vidyadharas (rig 'dzin 'dus pa rtsa ba'i rgyud) and is the fifteenth tantra within the Assemblage of Sugatas, an immensely detailed collection of teachings on the Eight Sadhana Teachings and associated Vajrayana material brought to Tibet by Padmasambhava and taught to his main disciple. The Assemblage of Sugatas was concealed as a terma and later revealed by Nyang Ral Nyima Oser. The practice of Guru Vidyadhara is expressed through the principle known as the four aspects of approach and accomplishment. The most detailed terma on this principle was revealed by Sangye Lingpa (1340-1396) and is still renowned as Lama Gongdu (bla ma dgongs 'dus) in 18 volumes of approximately 700 pages each. The Guru Vidyadhara is also the basis for innumerable sadhanas propagated by other tertons, for instance the Rigdzin Dupa cycle within the termas of Longchen Nyingtig as well as the Lamey Tukdrub Barchey Kunsel cycle revealed by Chokgyur Lingpa and Jamyang Khyentse Wangpo that are both widely practiced to this day. EPK