I bought another Osprey Campaign series book about the Battle of Zorndorf earlier this week. Although The Seven Years War lies outside my traditional hobby area, I am fascinated with the life and times of Frederick the Great. One of my motivations to keep in touch with the German language was that through German I was able to read some books by great authors on the subject. Some were better than others and some frustrated me more than others. Nowadays, I have forgotten so much German that whenever I go to my library to pick up a "Frederick book" the dictionary Ap on my iphone gets to thorough working over and I am often depressed about what I used to know compared to now.
Anyway, if you are a German reader, I recommend the definitive "recent" work on Frederick by Theodor Schieder. It is an Incredible book scholarship. Unfortunately being German ol' Theo has a genetic disposition to build sentences which are so long you have to go to another book to find the verb at the end!
My favorite book in English is Chris Duffy's Frederick the Great -A Military life. Dr Duffy's book really introduced the subject to me and even now a occassionally take out the book and skim through it. In fact, I took it out a few weeks ago and I can't find it to take a snap of the cover!