When Christa Landon first published her edition of Joseph Haydn's piano sonatas, Haydn's sonatas were still completely overshadowed by the works of Mozart and Beethoven. In the meantime, Haydn's sonatas have long since left the niche of piano lessons and have once again found their way into the concert hall; Landon's edition has played a major role in this. The Haydn anniversary in 2009 is a welcome opportunity for a thorough revision of this "legendary" edition, because in more than 40 years, new sources have come to light and questions of authenticity have been clarified; not least of all, the editorial principles for 18th century music have changed significantly. The new edition includes all the works from the previous Vienna Urtext edition, as well as the sonata Hob. XVI:16, which Landon had excluded, and a sonata in F major attributed to Joseph Haydn, which was rediscovered in Bolzano just a few years ago. The new edition is also divided into 4 volumes, the content of which is compatible with the previous edition. Volumes 1 and 2 contain the early sonatas. In the interpretation notes, Robert D. Levin explains key aspects of Haydn's performance practice.