Morgan, Robert P. “Rewriting Music History: Second Thoughts on Ives and Varèse.” Musical Newsletter 3, no. 1 (January 1973): 3-12, and 3, no. 2 (April 1973): 15-23, 28.
Kellers, Wilfred. “Realism and Transcendentalism: Charles Ives as American Hero.” In Music in a New Found Land: Themes and Developments in the History of American Music, 38-64. London, United Kingdom: Barrie and Rockliff, 1964.