Kling, Modern Orchestration and Instrumentation.
Henderson, The Orchestra and Orchestral Music; contains two chapters (XII and XIII) on the Orchestral Conductor that will be of great interest to the amateur.
Mason (Editor), The Art of Music (Vol. VIII).
Stoeving, The Art of Violin Bowing.
Forsyth, Orchestration. A particularly good book both for professional and amateur, as it gives many illustrations and treats the various instruments from an historical as well as a practical standpoint.
Widor, The Modern Orchestra.
IV. The Church Choir:
Curwen, Studies in Worship Music (two volumes).
Dickinson, Music in the History of the Western Church.
Helmore, Primer of Plainsong.