Main texts: The primary text we are using is The Heart of Compassion by Dilgo Khyentse Rinpoche. This commentary is quite comprehensive and touches on many foundational ideas of Mahayana and Vajrayana Buddhism. Dilgo Khyentse (1910-91) was a great master in the Nyingma lineage and a contemporary of Khyabje Kalu Rinpoche.
Other sources we’re using regularly are Reflections on Silver River by Ken McLeod, and personal notes I took while livestreaming Pema Chodron’s weekend retreat on the 37 practices at Omega Institute in 2016. (I can’t find any evidence that it’s available for purchase.) I also frequently refer to Khenpo Tsultrim Gyamtso Rinpoche’s commentary, The 37 Practices of a Bodhisattva, which includes the Tibetan and was originally published by the Marpa Institute but is out of print as far as I know. And as the class progresses, we call more often upon Transforming the Heart (translated by Thubten Chodron), a commentary by Geshe Jampa Tegchok, a highly regarded Gelugpa teacher. This commentary was invaluable when we studied verse 6: to rely on spiritual friends, and also for verse 8: to refrain from harm at all costs (karma).
In the later classes we also turn regularly to Traveling the Path of Compassion by His Holiness the Seventeenth Karmapa Ogyen Trinley Dorje, the head of the Karma Kagyu Lineage. And just as we were finishing the six paramitas (verses 25-30), His Holiness gave five sessions of livestreamed teachings on the 37 practices, which I highly recommend for a concise review, some insights not covered elsewhere in the commentaries (especially regarding the paramitas), and the blessings of receiving the teachings directly from HH Karmapa. Here’s the first link:
Since the 37 Practices falls within both the lam rim and the mind training traditions, we sometimes refer to the following indispensable texts:
For lam rim enrichment, we rely upon Gampopa’s all-encompassing guidebook to the path of awakening, Ornament of Precious Liberation (OPL), aka Jewel Ornament of Liberation (JOL). There are several translations. This one, by Ken Holmes, is the one I currently use most, but occasionally I prefer a translation in one of the other versions, particularly Khenpo Konchog Gyaltsen’s JOL. We also refer to Ringu Tulku’s concise and very accessible introduction to OPL, Path to Buddhahood. My copy’s had so much use over the years that it’s literally falling apart. Once in a while we pull in The Torch of True Meaning (aka The Torch of Certainty) by Jamgon Kongtrul Lodro Thaye, which is a step by step guide to the preliminary practices of the Karma Kagyu lineage.
For mind training enrichment, we rely mainly on The Great Path of Awakening by Jamgon Kongtrul, translated by Ken McLeod. We have also referred, especially in our study of verse 11, to Shantideva’s Guide to the Bodhisattva’s Way of Life, which is the third jewel in the crown of Kagyu mind training texts. It is available in various easily obtained translations as well as in pdf format.
For verses 8-10, the three levels of motivation for awakening, I also referred to Essence of Ambrosia by Taranatha, translated by Lama Willa Baker (Miller), since that is its very topic. In particular, I used the contemplations in chapter 3, “The Miseries of the Three Lower Realms,” as a basis for a guided meditation on verse 8.
A few other resources used once or twice are mentioned and usually linked within their respective posts.
These are all excellent books for any student of Buddhism, whether or not you are following the study guide, which begins here.