Robert Zoller's works:

• Tools and Techniques of the medieval Astrologers, ©1981; Spica Books, Queensland, Australia.
  If you are going to be a homegrown, self-taught Astrologer, I suggest this as one of your text-books. It is not for Beginner's, without a little coaching. Solid information with practical chart references.
  
  

• The Arabic Parts in Astrology – A Lost Key to Prediction, ©1980,1989; Inner Traditions International, Rochester, Vermont.

Dr. J. Lee Lehman's works:

• The Book of Rulerships – Keywords from Classical Humanity, ©1992, Whitford Press, West Chester, Pennsylvania
  A handy reference guide that lives in my backpack. Lee created one of the quickest and most useful tools for Astrologers who ask questions and want many opinions. This book relies wholly on Rennaissance and pre-Renn. Astrologers, then notes their initials next to the rulership (in case you want to find the rulership in the context of the original works).
  
  

Michael S. Schneider

• A Beginner's Guide to Constructing the Universe, The Mathematical Archetypes of Nature, Art and Science, A Voyage From 1 to 10.
  Sometimes Astrologers must know more than just Astrology. This Mathematician explains how geometry is found in organic nature and how it express itself in the numbers 1 through 10 (i.e., 6 sided objects are crystals in nature, not quickly changing and rather stable made of two triangles).
  

Anthony Louis's works:

• Horary Plain & Simple – Fast and Accurate Answers to Real World Questions, ©1998; Llewellyn Publications, Minneapolis, MN
  

Llewellyn George's works:

• A to Z Horoscope Maker and Delineator
  A modern work with a traditional approach.

Ancient Authors

Meira Epstein Translations:

• The Beginning of Wisdom, translation ©1998; ARHAT Publications
  Ibn Ezra is known amongst Jewish Scholars and families alike. He is known mostly for his brilliant understanding of Jewish law. His wonderful intelligence also was applied to explaining Astrology, briefly. This is one of the easiest books of medieval Astrology for a beginner to understand.

Robert Zoller Translations:

• Liber Astronomiae by Guido Bonnatti and translated by Robert Zoller (and Rob Hand).
  Bonnatti's work — with parts still in translation — is an encyclopedic examination of techniques of the medieval Astrologer. He references past masters and gives summaries of their interpretations, along with his own experienced descriptions of Astrology.

Dorian Giesler Greenbaum, M.A. translation:

• Late Classical Astrology: Paulus Alexandrius and Olympiodorus
  This is a useful, but difficult book. If I didn't already know the basic tools of medieval Astrology, I would have trouble wading through this. Doris Greenbaum has still brought forth an important work for our study.
  

Al-Biruni

Claudius Ptolemy

• Tetrabiblios
  William Lilly swore by it, I believe. Some moderns swear at it. Others swear by it, too. Really, this is one of the pillars of Western Astrology. Ptolemy, the scientific journalist, well-summed the rules of the Hellenistic-Egyptian Astrologers. Useful for weather prediction, vocational study, fame indications and for one of the doctrines on length of life.
  

Late Classical Astrology: Paulus Alexandrius and Olympiodorus
This is a useful, but difficult book. If I didn't already know the basic tools of medieval Astrology, I would have trouble wading through this. Doris Greenbaum has still brought forth an important work for our study.