Identifying planetary triggers, Celeste Teal
Synastry, Davison Ronald
Solar Arcs, Noel Tyl
The principals of Astrology, E.O. Carter
The art of predictive Astrology, Carol Rushman-good for beginners-
Planets in Composite, Hand Robert
Predictive Astrology, Frances Sakoian
The Lunation cycle, Dane Rudhyar
Symbolic Directions in Modern Astrology, E.O. Carter
Mundane Astrology the Astrology of nations and states, Liz Greene, Charles E.O. Carter
Only 10? It depends on what kind of astrology you are interested in.
One more that is of paramount importance:
Hellenistic Astrology, the study of fate and fortune, Chris Brennan
To begin with...there are many, many others of high importance that I use..