The Non-Existent Complex 6-Sphere
  The possible existence of a complex structure on the 6-sphere has been a famous unsolved problem for over 60 years. In that time many "solutions" have been put forward, in both directions. Mistakes have always been found. In this paper I present a short proof of the non-existence, based on ideas developed, but not fully exploited, over 50 years ago. The only change in v2. is in section 3, where the notation has been clarified. 
Michael Atiyah
math.DG