Drower, George (2011). Heligoland: The True Story of German Bight and the Island That Britain Forgot. Stroud, UK: History Press. ISBN 9780752460673. /wiki/ISBN_(identifier)
Drower, George (2011). Heligoland: The True Story of German Bight and the Island That Britain Forgot. Stroud, UK: History Press. ISBN 9780752460673. /wiki/ISBN_(identifier)