If you are a history guy who likes charts and numbers this book is essential.  Mine is a 1974 reprint which makes them somewhat available. One heck of a resource but you have to find it. Charts and detail galore and in fact at times seems random.  Tons of it organized several different ways.  It has frustrated me in that it has every conceivable pay chart except monthly pay.  How many types of each rank in each different type of unit. This was the source book fir many old Kaiserzeit articles and will be for me too. Regiment by regiment details but as I said you have to dig through pages to find it.  I often think of this as a farmer's almanac... a little bit of everything.  Definitely worth having.  It is not a book to read just a reference work. Loads of little details. Not a picture book.  A book of tables. I actually refer to it very often. Regularly in combination with other books. For some reason on conventions this book is referd to as Durch.