Teachings and Writings
The Bhagavad Gita. There are many versions but the versions by Swami Prabhupada and Stephen Mitchell are excellent.
The Upanishads. The Kena, Maitri, Mandukya,
and Taittiriya Upanishads are a good place to start.
The Secret of the Golden Flower. There is a version by Richard Wilhelm and Carl Jung, and another version by Thomas Cleary in which he corrects mistakes in the previous version. Both versions are valuable.
The Tao te Ching. I find the version by Stephen Michell to be most poetic and clear.
The Red Book. By Carl Jung.