Dedicated to his friend and pupil Archduke Rudolf, Beethoven's expansive Archduke Trio is his greatest work in the genre, though increasing deafness meant it also signaled his final appearances as a performer. The cheerful Piano Trio in E flat major is an earlier work, though only discovered amongst the composer's papers after his death, and the Kakadu Variations is another good humored work based on a popular song of the day. With the American Record Guide "impressed with every recording", Volumes 1 (8.557723), 2 (8.557724), 3 (8.570255) and 4 (8.570943) are also available.