- Libro electrónicoThe First Studies for Every Piano Student as the Technical Foundation for VirtuosityLouis Köhler
- Libro electrónicoKöhler - The Easiest Exercise Pieces for piano Op.190Louis Köhler
- Libro electrónicoKöhler - Little School of Piano Velocity Op.242Louis Köhler
- Libro electrónicoKöhler - New School of Velocity for Piano Op.128Louis Köhler