A Cascading Waterfall of Nectar — by Thinley Norbu

Original work on the ngöndro practice of Tibetan Buddhism, rich with scriptural citations, incisive reasoning, and personal realization.

The Great Gate for Accomplishing Supreme Enlightenment – translated by Erik Pema Kunsang

A Guide Book to The Preliminary Practices of Lamey Tukdrub Barchey Konsel, The Guru's Heart Practice, Dispeller Of All Obstacles

Not for Happiness - A Guide to the So-Called Preliminary Practices — by Dzongsar Jamyang Khyentse

Everything an aspiring practitioner needs to get started the Ngöndro practice.

Longchen Nyingtik Practice Manual — by Dzongsar Jamyang Khyentse Rinpoche

Advice on how to practice - based on Jamyang Khyentse Wangpo's Short Preliminary Practice.

The Crystal Mirror - Clearly Showing All The Steps By Which The Path Of Liberation Is Traversed In This Fortunate Kalpa — by Kalu Rinpoche

Teaching on the Kagyu Mahamudra preliminary practices, given by Rinpoche during the Kalachakra initiation in the early eighties in New York.

Ngondro Commentary - Instructions for the Concise Preliminary Practices of the New Treasure of Dudjom

A practical and accessible guide for students to use in directly engaging the preliminary practices, which establish the foundation for the entire Vajrayana path.

The Jewel Ladder - A Preliminary Nyingma Lamrim — by Gyurme Dorjee

This commentary by Khamtrul Rinpoche given in simple and lucid language unravels the gist of Rin-chen them-skas.

The Words of my Perfect Teacher — by Patrul Rinpoche

Classic commentary on the preliminary practices of the Longchen Nyingtig - one of the best-known cycles of teachings and a spiritual treasure of the Nyingmapa school - the oldest Tibetan Buddhist tradition.

Guru's Heart Practices - Texts for Dispeller of Obstacles  — by Padmasambhava

This extensive cycle contains teachings and practices for the preliminaries up to and including Dzogchen.

Guru Yoga - According to the Preliminary Practice of Longchen Nyingtik — by Dilgo Khyentse Rinpoche

This particular guru yoga is called "The Wish-fulfilling Jewel" and it is the outer practice of the guru from the Longchen Nyingtik revelation of Rigdzin Jigme Lingpa.