Hi Rich,
Walter Waiss is a well-regarded Luftwaffe researcher who has authored or co-authored many high-quality books on a range of subjects.
Here are the ones I'm aware of:
- "Chronik Kampfgeschwader Nr. 27 Boelcke" (seven volumes), self-published (vols. 1-3) & Helios (vols. 4-7), 1997-2010 (Note: A revised edition of Vol. 4 was published in 2014)
Definitive history of KG 27. As Chris mentioned, the first 3 volumes are kinda crappy softcover bindings, but the last 4 volumes are excellent hardcovers.
- "Legion Condor" (8 volumes), Helios, 2013-2025
A detailed and well-illustrated series of books on the Luftwaffe in the Spanish Civil War.
- "Kommando Bienenstock: Letzter Einsatz der Luftwaffe Mai 1945", Helios, 2021, ISBN 978-3-86933-270-3
Features many personal accounts of the desperate attacks on Soviet armored columns using Bü 181s fitted with Panzerfausts. Also includes some accounts from Kommando Elbe participants.
- "Heinz Sannemann: Ein Jagdfliegerleben", Helios, 2018, ISBN 978-3-86933-218-5 (co-authored with Falk Breuer)
A biography consisting of the photos, correspondence and diary entries of Heinz Sannemann, who flew with JG 26, JG 3, and EJG 1.
- "Überlebt: Das Fliegerleben des Georg Munker 1939-1945", Helios, 2012, ISBN 978-3-86933-074-7
A photographic account of Munker's service as a photojournalist. He flew with various Luftwaffe units, including KG 27.
- "Von Caen zur Festung Sewastopol: Stationen eines Bordinstrumentenprüfers in der Luftwaffe 1937-1942", Helios, 2014, ISBN 978-3-86933-110-2
A photographic account of Herbert Heise's service as an instrument tester on the Western and Eastern fronts. Includes his Flugbuch.
Waiss also assisted Max Lagoda with his autobiography, "
Ein Blick in die Vergangenheit: Kriegserinnerungen eines Fernaufklärers aus Russland und dem Orient", Helios, 2011, ISBN 978-3-86933-047-1
I'd very much appreciate an English edition of any (or all) of the KG 27 volumes.
Hope that helps,
Leon Venter