There are a few books to which I return, some provide inspiration whilst others are just a plain good read. The first book is the inspiration type, lots of great ideas as it reflects my own interests in smaller railways of Oberfranken.
These are my go-to books for understanding the various regional nuances within Germany - they are much more than a coffee-table decoration - find a copy.
And two wonderful, non-railway books.
Not a huge collection of books, just a few that are relevant to anyone wishing to build a layout in Frankenland.
Finally, an excellent book for those interested in the KBayStsB, it is full of images and diagrams.