Nice find Karl. I've seen this profile and picture before. However, Osprey's book isn't really accurate in all regards. The profile of "Yellow 11" is clearly based on the profile posted in post #8 on previous page and only replicates it's inaccuracies regarding yellow underside of the engine cowling and outline type of fuselage Balkenkreuz.
Also, the picture you posted does indeed show Ján Gerthofer, but aircraft behind him isn't "Yellow 11". It's another aircraft of Letka 13 with similarly spotted engine cowling - Bf 109G-4 "Yellow 6" W.Nr.19330. Check the series of pictures of Gerthofer and this aircraft taken from different angles as published in HTmodel Špecial No.912 (pg 31).
ok loads of nice info there Igor i'll leave this thread for you to help Andy, you know more about it than me !!!!