Enlightenment by a single means: Tibetan controversies on the "self-sufficient white remedy" (dkar po chig thub)
"Analysis of the debate over mahāmudrā between Sa skya pas and Bka' brgyud pas; contains much useful information on and extracts from the writings of Sgam po pa and Zhang tshal pa" (Roger R. Jackson, “Mahāmudrā,” in Encyclopedia of Religion, ed. Lindsay Jones, 2nd ed. (Detroit: Macmillan Reference USA, 2005), vol. 8, p. 5601).