I have found Norbert Hannig's book Luftwaffe Fighter Ace online:
http://www.walk77.com/dog/files/luft...ighter_ace.pdf
However, I find it sometimes confusing when Mr Hannig uses the term 'Staffelkapitän' instead of the captain's name, and one has to go a few pages back to find out whom he means. For example, on page 123, he says:
'The Staffelkapitän went down with appendicitis and had to go into hospital for an operation.'
Does he mean Udo Hünefeld (p. 115: 'The Staffelkapitän of 1/JGr Ost was Oberleutnant Udo Hünefeld, he of the short match drawn when it had been time to vacate Kiev-West.'), or maybe Emil 'Bully' Lang (p. 113: 'My Staffelkapitän, Leutnant Emil Lang, had already been informed.')?