C. E. Bretherton to I. E. Requa, May 16, 1894 CPH Papers, ser. 1, r. 53.
CPH to Gates, May 8, 1890 CPH Papers, ser. 1, r. 48.
Daggett, Chapters, 136-38.
William Mahl, Memoirs: P.I. Co., G18, Mahl Papers.
C. F. Crocker to CPH, Sept. 3, 1891, CPH ser. 1, r. 50.
Mahl Memoir, E. H. Harriman, O-3, O-4, O-5, Mahl Papers.
J. T. Mahl to William Mahl, Sept. 23, 1895, William Mahl to J. T. Mahl, Jan. 30, 1899, Mahl to Father, Feb. 7, 1899, J. T. Mahl to Father, March 7, 1899, box 2E460, Mahl Papers.