A famous book on horary is written by Olivia Barclay Horary Astrology Rediscovered Whitford Press.
Barbara Dunn is a student of traditional astrologer Olivia Barclay, and Horary Astrology Re-Examined , The Wessex Astrologer, is based on Barclay’s book.
Christopher Warnock published Warnock’s Horary Case Book, 40 charts of questions and their delineation, all from his own practice.
And if you like detectives, search for Barbara Watters, The Astrologer looks at Murder, Valhalla Paperback.
Horary Astrology and the Judgment of Events written by Barbara Watters.
Lee Lehman is one of my teachers and her book Classical Astrology for Modern Living is, according to Dave Roell, Astroamerica, “A mixture of shrewd historical commentary, coupled with explanation & analysis of classical (eg, traditional) astrology. An excellent, absorbing book”.
Her book The Martial Art of Horary Astrology, Whitford Press, is a modern classic on horary.