Beethoven, L. v., & Kail, R. (1980). World's favorite classic & romantic piano duets: For one piano-four hands by Beethoven ... [et al.]. Ashley Pub.
Lua i Stíl Chicago (17ú heag.)Beethoven, Ludwig van, agus Robert Kail. World's Favorite Classic & Romantic Piano Duets: For One Piano-four Hands by Beethoven ... [et Al.]. New Jersey: Ashley Pub, 1980.
Lua MLA (9ú heag.)Beethoven, Ludwig van, agus Robert Kail. World's Favorite Classic & Romantic Piano Duets: For One Piano-four Hands by Beethoven ... [et Al.]. Ashley Pub, 1980.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.