C. F. Crocker to CPH, Dec. 22, 1893CPH Papers, ser. 1, r. 52.
C. F. Crocker to CPH, June 28, 14, 1892 (letter and telegram), June 19, 30, July 5 (two letters), 1893, CPH to C. F. Crocker, June 16, 1893, all in CPH Papers, ser. 1, r. 52.
CPH to C. F. Crocker, July 7, 1893, CPH Papers, ser. 1, r. 52.
CPH to C. F. Crocker, July 18, 1893, CPH Papers, ser. 1, r. 52.
CPH to C. F. Crocker, July 17, 12, 1893, C. F. Crocker to CPH, July 26, 12, 1893, CPH Papers, ser. 1, r. 52.
Mahl, "Memoirs: P.I. Co.," G4, Mahl Papers.