Dial Detective: Investigating with the 90 Degree Dial, Maria Kay Simms, revised 2nd edition, Cosmic Muse Publications. *
Rules for Planetary Pictures, Alfred Witte and Herman Lefeldt, Penelope Publications. *
Various online articles:
•Symmetrical Astrology: An Overview of Its Origins, Gary Christen.
•Planetary Pictures: An Introduction, Gary Christen.
•Planetary Pictures 101, Gary Christen.
* Available from Astrolabe Inc. on the Books page.
