This book is probably the one I refer to most often. It was written by Nick Beer, formerly senior tutor at the Charles H Cecil Studio in Florence and the principal of Sarum Studio in Salisbury (see under Websites for more information). It has formed the backbone of my self-directed study over the last few years.
Its very nicely written and contains extremely useful information, particularly on materials and painting mediums and the 'philosophy' of naturalistic painting. The book follows a series of projects from cast drawing I'd highly recommend picking up a copy to anyone interested in studying classical drawing and painting.
Ben Laughton Smith
Aspiring artist, training in the classical tradition.