Andy,
Thank you for the additional references. I will try and comment on the first reference.
From the Bibliography listed on his website, it would appear that Michael Holm was fully aware of references No. 2 and 3, as follows:
Aders, Gebhard: History of the German Night Fighter Force, 1917-1945; Jane's Publishing Company, London, 1979
Caldwell, Donald: The JG26 war diary, 2 vols.; Grub Street, London, 1996 - 1998
I can only suspect that in his reference he ultimately opted for Prien, Stemmer and others book, JFV der Deutschen Luftwaffe 1934-45, Vol.2. The key word here again is "apparently".
Another reference on the web can be found here
http://www.lexikon-der-wehrmacht.de/...wader/JG26.htm . This one also referred to Prien/Rodeike/Stemmer/Bock, Die Jagdfliegerverbände der Deutschen Luftwaffe 1934 bis 1945, mehrere Bände.
Regards,
Sinisa