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2. Mullin GH (1997) Readings on Six Yogas of Naropa (Snow Lion Publication, Ithaca, NY).
3. Mullin GH (1996) Tsongkhapa’s Six Yogas of Naropa (Snow Lion Publication, Ithaca, NY).
4. David-Neel A (1971) Magic and Mystery in Tibet (Dover Publications, New York).
5. Govinda Lama Anagarika (1988) Way of White Clouds (Shambhala Publications,).