I have listed one or two books from authors I like. If you find an author you like, read more from that person.

SHYAM, SWAMI. Various Books. Order online.

DALAI LAMA. The Way to Freedom. New York, NY: Harper Collins, 1994.
DALAI LAMA. The Heart of Meditation. Boulder: Shambhala, 2016. 

SOGYAL RIMPOCHE. The Tibetan Book of Living and Dying. ISBN:9781846041051, Rider, 1992.

NISARGADATTA, SRI. I Am That. Durham, NC: Acorn, 1973.
NISARGADATTA, SRI. Nothing Is Everything, Zen Publications, 2014.

SUZUKI SHUNRYO.  Zen Mind, Beginner’s Mind. New York, NY: Weatherhill, 1970.
THICH NHAT HANH. The Art of Power. Harper One, 2007.
PEMA CHODRON. Start Where You Are. Boston, MA: Shambala, 1994.
SHAH, INDRES. The Way of the Sufi. Toronto, ON: Penguin, 1968.

JOHN O’DONOHUE. Beauty,  New York, NY: HarperCollins, 2004.
TRUNGPA CHOGYAM. Cutting Through Spiritual Materialism, Boulder, CO: Shambhala, 1973.
GOLEMAN, DANIEL. Emotional Intelligence. New York, NY: Bantam, 1995.
HESSE, HERMAN. Siddhartha. Tandem, 1951.
EPSTEIN, MARK. Going to Pieces Without Falling Apart. New York, NY: Broadway Books, 1998.

SHARON SALZBURG.  The Force of Kindness. Boulder, CO: True Sounds, 2005.
FEURSTEIN, GEORG. The Deeper Dimensions of Yoga. Rochester, VT: Inner Traditions, 2003
MUKUNDA STILES. Yoga Sutras of Patanjali. San Francisco, CA:  ed Wheel/Weiser,  2002.
IYENGAR, BKS. Light on the Yoga Sutras of Patanjali. San Francisco, CA:  Aquarian/Thorson, 1993.
STOLER-MILLER, BARBARA. Yoga: The Discipline of Freedom. New York, NY: Bantam, 1998.
DOGEN. Zen Meditation.