Concerto for two pianos No.10 in E-flat major, KV 365

It is not known when Mozart completed his concerto for two pianos in E-flat major, K. 365/316a, but research by Alan Tyson shows that cadenzas for the first and third movements are written in his and his father's handwriting on a type of paper used between August 1775 and January 1777[citation needed]. However, most sources, including Alan Tyson's book "Mozart: Studies of the Autograph Scores" (1987) or more recent Lindeman's "The Concerto: A Research and Information Guide" (2006) indicate that it was composed in 1779. This date was retained on Wikipedia pages for K.365/316a in any other language. It is presumed that Mozart wrote it to play with his sister Maria Anna (“Nannerl”). Years later he performed it in a private concert with pupil Josepha Barbara von Auernhammer.