ماخذ: Chopinesque Etude No. 1 in D Minor. , he only used 15 different keys. Samuel Wellman. Piano Method sheet music. Advanced.
ترجمه: " I listed the 9 unused ones and decided to write an etude in each of those keys, while imitating. ساموئل ولمن. موسیقی نت پیانو روش.