THE PRACTICE OF DZOGCHEN IN THE ZHANG-ZHUNG TRADITION OF TIBET, containing 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 Seven-fold Cycle of the Clear Light,” being the Dark Retreat practice from the same tradition, translated with commentaries and notes by John Myrdhin Reynolds