Letter from Wilder Penfield to Charles F. Martin, May 9, 1934.
Letter from Wilder Penfield to Charles F. Martin, November 8, 1929.
Letter from Wilder Penfield to Charles F. Martin, November 9, 1931.
Letter from Wilder Penfield to Charles F. Martin, October 18, 1932.
Letter from Wilder Penfield to Charles F. Martin, October 19, 1928.
Letter from Wilder Penfield to Charles F. Martin, September 20, 1934.
Letter from Wilder Penfield to Charles Martin, February 11, 1928.
Letter from Wilder Penfield to Charles Martin, February 14, 1928.
Letter from Wilder Penfield to Charles Martin, February 2, 1931.
Letter from Wilder Penfield to Charles Martin, January 14, 1928.
Letter from Wilder Penfield to Charles Martin, January 17.
Letter from Wilder Penfield to Charles Martin, Janurary 24, 1928.
Letter from Wilder Penfield to Charles Martin, March 14, 1933.
Letter from Wilder Penfield to Charles Martin.
Letter from Wilder Penfield to Charles Miller Fisher, August 1, 1946.