Ludwig van Beethoven, Brief an Tobias Haslinger, Wien, nach dem 9. und vor dem 23. Januar 1817, Autograph

Beethoven informs the publishing assistant Haslinger of the exact words for the title of op. 101 as well as the dedication. Should the title page already have been printed, he asks him to have a new one made at his (Beethoven's) expense or to keep the new title for his next sonata. In addition he asks him to show the term "Hammer-Klawier" to a language expert to ensure that it really is German. (In the end the word "Hammerklavier" appeared on the title page.)

Earlier on Beethoven had already thought about translating the Italian term "Pianoforte" into German, considering "Hammer-", "Hämmer-Klavier" and "Hämmer-Flügel".