Since's this is an AP forum i can start with "Astral Projection - The Out Of Body Experience" by Denning & Philips as a well "goes together" with Robert Bruce's works.

Heinrich Cornelius Agrippa - Books On Occult Philosophy
Franz Bardon's works
Takuan Soho - The Unfettered Mind
Yagyu Munenori - The Life Giving Sword
Wilhelm Reich's Works
Israel Regardie's Works
H.P. Blavatsky's Works
Karl Von Eckarthausen - The Cloud Upon The Sanctuary
John Michael Greer - The Complete Picatrix
- Tao Te Ching
William Walker Atkinson (Yogi Ramacharaka) - The Science Of Breath
Translations of the Emerald Tablet of the Hermes Trimegistus
- Kybalion
Michael Harner - The Way of the Shaman
Other spectacular authors
Eliphas Levi, Austin Osman Spare, A.E Waite, MacGregor Mathers, Dion Fortune(Violet Firth), C.W Leadbeater, Carl Gustav Jung, Donald Tyson, Francis Barrett

!-> Most of the above books are free and Sacred-Texts.com and Hermetics.org has great archives.

Other General
Works on Sufism, works of old greek philosophers.