Maxim Shrayer, the leading investigor of Nabokov's short stories (see his 1999 THE WORLD OF NABOKOV'S SHORT STORIES) provides an excellent survey of the evolution of the relationship between Nabokov and fellow Russian writer Ivan Bunin (Nobel Prize 1933). Shrayer's  survey and co-presentation  (with R.Davies) of the correspondence of the writers appears in the new Russian Academy of Sciences  Gorki Institute volume S DVUX BEREGOV: RUSSKAYA LITERATURA xx VEKA V ROSSII I ZA RUBEZHOM (2002), pp. 167-219.