. Academy Chicago, 1982.Brennan, J. H. The Astral Projection Workbook
. Sterling, 1990.Bruce, Robert. Astral Dynamics
. Hampton Roads, 1999.Buhlman, William L. Adventures Beyond the Body: How to Experience Out-of-Body Travel
. Harper SanFrancisco, 1996.Crookall, Robert. Study and Practice of Astral Projection
. University Books, 1966.Dennet, Preston. Out-Of-Body Exploring: A Beginner's Approach
. Hampton Roads, 2004.Denning, Melita, and Osborne Phillips. Practical Guide to Astral Projection
. Llewellyn, 1979.Eby, Carol. Astral Odyssey: Exploring Out-Of-Body Experiences
. Samuel Weiser, 1996.Elder, Paul. Eyes of an Angel: Soul Travel, Spirit Guides, Soul Mates, and the Reality of Love
. Hampton Roads, 2005.Fox, Oliver. Astral Projection
. Citadel Press, 1962.Frost, Gavin, and Yvonne Frost. Astral Travel
. Samuel Weiser, 1982.Green, Celia. Out of the Body Experiences
. Hamish Hamilton, 1968.Greenhouse, Herbert B. The Astral Journey
. Doubleday, 1975.Harary, Keith, and Pamela Weintraub. Have an Out-of-Body Experience in 30 Days: The Free Flight Program
. St. Martin's Press, 1989.Hughes, Marilynn. Odysseys of Light
. Hampton Roads, 1991.Martin, Anthony. The Theory and Practice of Astral Projection
. Aquarian Press, 1980.McCoy, Edain. Astral Projection For Beginners
LLewellyn, 1999.Mitchell, Janet Lee. Out-of-Body Experiences: A Handbook
. Ballantine, 1981.Moen, Bruce. Voyages into the Unknown
. Hampton Roads, 1997.Monroe, Robert A. Journeys Out of the Body
. Doubleday, 1971.Monroe, Robert A. Far Journeys
. Doubleday, 1985.Monroe, Robert A. The Ultimate Journey
. Doubleday, 1994.Muldoon, Sylvan, and Hereward Carrington. Projection of the Astral Body
. Samuel Weiser, 1929.Muldoon, Sylvan, and Hereward Carrington. The Phenomena of Astral Projection
. Samuel Weiser, 1951.Ophiel. The Art and Practice of Astral Projection
. Samuel Weiser, 1961.Peterson, Robert. Out of Body Experiences: How to Have Them and What to Expect
. Hampton Roads, 1997.Powell, Arthur E. The Astral Body: And Other Astral Phenomena
. Theosophical Publishing House, 1926.Richards, Steve. The Traveller's Guide to the Astral Plane
. Aquarian Press, 1983.Rogo, D. Scott. Leaving the Body
. Prentice-Hall, 1983.Shirley, Ralph. The Mystery of the Human Double: The Case for Astral Projection
. University Books, 1965.Stack, Rick. Out-Of-Body Adventures
. Contemporary Books, 1988.Taylor, Albert. Soul Traveler: A Guide to Out-of-Body Experiences and the Wonders Beyond
. Dutton, 1998.Vieira, Waldo. Projections of the Consciousness: A Diary of Out-of-Body Experiences
. International Institute of Projectiology and Conscientiology, 1997. (Originally published in Portuguese in 1981.)Webster, Richard. Astral Travel For Beginners: Transcend Time and Space with Out-of-Body Experiences
. Llewellyn, 1998.Yram. Practical Astral Projection
. Samuel Weiser, 1967.I recommend the highlighted books. Bruce's book is valuable for it's energy exercises, rope-projection technique, and the author's descriptions of other dimensions. The book by Rogo is an excellent introduction to projection and provides broad objective coverage of the topic. Many techniques of inducing projections are explained and evaluated by the author. The early Muldoon book is an important detailed reference covering certain types of projections. That classic has been reprinted many times and it is still available. Elder's book is about much more than out-of-body experiences. Elder offers wonderful information on life's purpose, spirit rescue, soul mates, reincarnation, spirit helpers, and love. The three Monroe books have affected me and my worldview more than any of the others. If you limit yourself to one author, I recommend Monroe.
Note: The editions listed above are the copies I own, not necessarily the editions available through the title links.