He was the editor of the piano works of Claude Debussy, Erik Satie, Gabriel Fauré, Louis Moreau Gottschalk, Hermann Scherchen and Scott Joplin as well as of Gustav Mahler's Symphony No.
At the same time, he published historical works by Charles Burney, Claude Debussy, Anton Felix Schindler and George Bernard Shaw.
In the field of contemporary music, he conducted research on composers such as Alban Berg, Béla Bartók, Claude Debussy, Charles Ives, Max Reger, Gustav Mahler, Erik Satie, Karol Szymanowski, Arnold Schoenberg and Edgar Varèse.
As a music theorist, Klemm corresponded with personalities such as Theodor W. Adorno, Manfred Bierwisch, Ernst Bloch, Konrad Boehmer, Carl Dahlhaus, Ulrich Dibelius, Peter Gülke, Hans G Helms, Uwe Johnson, Mauricio Kagel, Georg Knepler, Aloys Kontarsky, Erwin Ratz, Alfred Schnittke, Rudolf Stephan, and Hans Heinz Stuckenschmidt.
[2] With the musicians Gerd Schenker, Matthias Sannemüller and Steffen Schleiermacher, he founded the Forum Zeitgenössischer Musik Leipzig in 1990.