Trio in E-flat major, Op. 40 - Violin, Horn (or Viola or Cello) and Piano

Brahms composed his Horn Trio in 1865, in which year it was also first performed.  It was first published in 1866.  The manuscript score is digitized at the Library of Congress. 

In addition to the basic parts for violin, horn in E-flat, and piano, the Baerenreiter publication includes parts for viola (substitute for horn) and cello (substitute for horn).  Preface and editorial remarks.