Flying High Performance Singles and Twins by John C Eckalbar.
John Eckalbar is one of the original ground and flight instructors in the American Bonanza Society's, Bonanza and Baron Pilot Proficiency Program. He is also a professor in the Californian State University system and has published many articles on mathematics for economists and been the principal investigator on a National Science Foundation research project on dynamics and stability. (Lifted from his back cover bio.)
The 400 page hard cover book is highly recommended by John Deakin, Pelicans Perch Avweb contributor.
This book will take you from the rudimentary basics through to an advanced level of knowledge way beyond what you would typically find in Australian pilot shops, twin training manual theory literature.
By the end of the book you will be able to easily understand how to calculate ASDR without published POH data, the real correct actions in EFATO and why. Dispel a myth or three along the way, like why carrying 5 degrees of bank toward the live is incorrect and how to calculate the correct angle for your particular type.
A great read, and for any professional light/medium twin driver a book that should be the centre piece on your shelf.
Can be sourced through Amazon books on the web.