Books:

Free PDFs Available Here:

Practical Insight Meditation - Mahasi Sayadaw

The Progress of Insight (Visuddhiñana-katha) - Mahasi Sayadaw

The Sixteen Stages of Insight - Phra Dhamma Theerarach Mahamuni

For Purchase (Amazon Links):

Mastering the Core Teachings of the Buddha - Daniel Ingram

The Science of Enlightenment: How Meditation Works - Shinzen Young

Radical Acceptance: Tara Brach