Practice of Dzogchen in the Zhang-Zhung Tradition of Tibet from Vajra Publications, contains translations from the Bonpo Dzogchen practice manual for the Zhang-zhung Nyan-gyud, known as the Gyalwa Chaktri of Druchen Yungdrung, and from the Odsal Dunkor, The Sevenfold Cycle of the Clear Light, being the Dark Retreat practice from the same tradition, translated with commentaries and notes by John Myrdhin Reynolds. 

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