I will say that Jeppesen Multi Engine Manual is simply the best. I personally know of around 15 - 20 people who have read and then subsequently tested and passed. It's not just the passing but the fact that they know the aerodynamic affects of Vmc and all the associated Twin Engine aircraft problems without having to have a brain transplant bodes well with me. Like many other European manuals, the other European books on this subject are simply over the top & way too heavy.
This book (soft back) is a little bit more expensive than the other books but it is worth every penny because of the way it is written. I think it's available from Transair, Pilotwarehouse, .....
Remember one of the core principles of Instructing.......easy to difficult..............
Adios.