An Advanced Guide to Enochian Magick: A Complete Manual of Angelic Magick (Llewellyn's high magick series)
Gerald Schueler and Betty Schueler have authored five other books on Enochian magick.  They have also coauthored many articles on anthropology, computers, children, dogs, philosophy, magic and Theosophy.  Gerald is a retired systems analyst and Betty is a computer consultant.