Stockhausen: Gruppen ("Groups") for three orchestras

Stockhausen: Gruppen ("Groups") for three orchestras
３群のオーケストラのための「グルッペン」　（Japanese）

"Gruppen ("Groups") for three orchestras" (1955–57) is a very famous piece composed by Karlheinz Stockhausen. This piece is absolutely unique in orchestral formation (three conductors and three small-scale orchestral units).  Furthermore, this piece includes distinguishing features. The following web page explains clearly various features of this piece. Read Sounds in Space

Reference: "Gruppen" means "Groups" in English