For Jasta 18 planes I would go with Osprey Publishing "Jasta 18–The Red Noses " by Greg Van Wyngarden. It is full of great information on the Jasta 18 fighter group. Plus lots of photos and color profile and plan forms for excellent documentation. This book is number 40 in the Osprey “Aviation Elite Unit” series and it provides combat history for pilots such as Rudolf Berthold, Josef Veltjens and Paul Strahle and August Raben to name a few. I have not looked to see if its still in print. Nice thing about the Balsa USA DVII is that so many of us have built one, there is a lot of help out in RCU land.