When Christa Landon presented her printed edition of Joseph Haydn's piano sonatas for the first time, Haydn's sonata works were still overshadowed by the works of Mozart and Beethoven. But Haydn's sonatas left the niche of piano lessons long since and have become established in the concert repertoire; Landon's edition certainly played a major role in that. The Haydn anniversary in 2009 is a welcome occasion to thoroughly revise this 'legendary' edition, because new sources have been discovered and questions concerning authenticity have been clarified over more than forty years; the editorial principles for 18th-century music in particular have markedly changed in the mean time. The new edition comprises all the works from the previous Wiener Urtext edition plus the Sonata Hob. XVI:16 arranged by Landon, as well as a Sonata in F major which was discovered in Bolzano a few years ago and attributed to Joseph Haydn. The new edition, too, is divided into four volumes, the content of which is compatible with that of each of the volumes of the preceding edition. In the notes on interpretation Robert D. Levin explains essential aspects of Haydn's performance practice.