In music, Op. 20 stands for Opus number 20. Compositions that are assigned this number include: * Barber – Excursions * Bartók – Eight Improvisations on Hungarian Peasant Songs * Beethoven – Septet * Britten – Sinfonia da Requiem * Chausson – Symphony in B-flat * Chopin – Scherzo No. 1 * Dvořák – Moravian Duets * Elgar – Serenade for Strings * Haydn – String Quartets, Op. 20 * Hindemith – Das Nusch-Nuschi * Knussen – Where the Wild Things Are * Korngold – Das Wunder der Heliane * Matthay – Piano Quartet * Mendelssohn – Octet * Prokofiev – Scythian Suite * Rachmaninoff – Spring * Ries – Cello Sonata No. 2 * Sarasate – Zigeunerweisen * Schoenberg – Herzgewächse * Schumann – Humoreske * Scriabin – Piano Concerto * Shostakovich – Symphony No. 3 * Strauss – Don Juan * Tc