Ludwig van Beethoven, Friedrich Kerst, Henry Edward Krehbiel (1964). “Beethoven, the Man and the Artist, as Revealed in His Own Words”, p.106, Courier Corporation
Ludwig Van Beethoven, John Trie (2017). “Ludwig Van Beethoven for Classical Guitar - Tablature: Arranged for Guitar by John Trie”, p.31, BoD - Books on Demand
Ludwig van Beethoven (1868). “Letters from the Collection of Ludwig Nohl: Also His Letters to the Archduke Rudolph, Cardinal-Archbishop of Olmütz, K.W. from the Collection of Ludwig, Ritter Von Köchel. Translated by Lady Wallace, with a Portrait and Facsimile”, p.88