With trumpeters, trombonists in German city-states were employed as civil officials. Today, first-chair professional orchestral tenor trombonists are expected to play the alto trombone when required. Coker appeared on J.J. Johnson's "Trombones Incorporated" session featuring ten trombonists. Johnson was one of the earliest trombonists to embrace bebop. Gianluca Petrella is internationally considered one of the best young jazz trombonists. He was one of the most influential trombonists of early jazz. This is an alphabetical list of jazz trombonists for whom Wikipedia has articles. They were accompanied by Helmut Volke (Hammond organ) and seven trombonists led by Michael Struck. He has taught many prominent trombonists, including Christian Lindberg. Early trombonists adjusted pitch with the slide, and by adding variously shaped and sized crooks. He is considered one of the most technically able and talented trombonists of his generation.