Manookian, J. (1997). Gradus: Progressive piano repertoire in six volumes. Windsor editions.
Cita Chicago (17th ed.)Manookian, Jeff. Gradus: Progressive Piano Repertoire in Six Volumes. Canadá: Windsor editions, 1997.
Cita MLA (8th ed.)Manookian, Jeff. Gradus: Progressive Piano Repertoire in Six Volumes. Windsor editions, 1997.
Atenció: Aquestes cites poden no estar 100% correctes.