Kaspar Karl van Beethoven, Brief an Nikolaus Simrock in Bonn, Wien, 25. Mai 1803, Autograph

Between 1802 and 1806 Kaspar Karl, Beethoven's younger brother, organized Ludwig's business affairs and had contact with the publishers (who were apparently scared of his hard negotiation methods). Karl also offers some of his brother's works to the Bonn publisher Simrock, with whom Beethoven had earlier worked. He stipulates the condition that the works have to be published simultaneously in London, Leipzig, Vienna and Bonn. It was not unusual to produce parallel editions such as these. None of the publishers lost out if the publication date was the same and was discussed in advance.

Karl offers him the Kreutzer Sonata op. 47 for 30 ducats and the Third Symphony op. 55 for 400 florins (at the time the letter was written, Beethoven had not yet completed the Eroica, he only did so in the autumn of that year). Simrock bought op. 47 (the original edition appeared in April 1805), but not the symphony (which was published by the Industriekontor in October 1806).

In April 1803 Beethoven's Piano Sonatas op. 31,1 and 2 had been published by Nägeli in Zurich - an edition which was full of mistakes. Beethoven was disgusted and extremely angry about this edition and first of all considered publishing a list of mistakes in the most important newspapers. However, in the end he decided differently: Karl asks Simrock in this letter whether he would be interested in doing a completely new and correct edition of both sonatas. If so, he would send him a list of mistakes. Simrock agreed to do so and in the autumn of the same year published an "Edition tres correcte".

As with other publishers, Karl also offers him arrangements of his brother's works for piano with and without quartet accompaniment, made by Franz Xaver Kleinheinz and supervised by the composer.