アカペラ

Oh Christmas Tree
from CoolSide of Yuletide

Oh could we do
Imagination for Chorus with Lyrics by Thomas Moore

Old American Songs I, No. 2 The Dodger (SATB)
No. 2 The Dodger

Old American Songs I, No. 3 Long Time Ago (SATB, a cappella)
No. 3 Long Time Ago

Old American Songs I, No. 3 Long Time Ago (unison choir)
No. 3 Long Time Ago

Old American Songs II, No. 3 The Golden Willow Tree (SATB)
No. 3 The Golden Willow Tree

Old American Songs II, No. 4 At the River (SATB, a cappella)
No. 4 At the River

Old American Songs II, No. 5 Ching-a-Ring-Chaw (SATB, a cappella)
No. 5 Ching-a-Ring-Chaw

Old Fox Wassail

Old Joe Clark
American Folk Song

On Desire

On the Rio

On the Rooms

One day by the river a young Cossack roamed

One Equal Music

One for frost, two for fire

One Hand, One Heart (mixed choir (SATB) a cappella)
from West Side Story

Oolichan

Oratio - Pater noster

Oratio nocturna
Herr, sei uns gnädig