CPH to Hopkins, May 19, 1871, Huntington Letters, 3:276, also CPH to Hopkins, Nov. 2, 1870, Huntington Letters, 3:212.
CPH to Stanford, Nov. 5, 1870, Huntington Letters, 3:214.
CPH to Hopkins, Nov. 11, 1873, LB, 5:181, box 22, Hopkins Collection.
Cohen to CPH, March 24, 1875, CPH Papers, ser. 1, r. 7.
Cohen to CPH, April 27, 1875, CPH Papers, ser. 1, r. 8.
D. O. Mills to CPH, Nov. 16, 1875, CPH Papers, ser. 1, r. 8.
CPH to Hopkins, March 21, 1876, LB, 8:119, box 23, Hopkins Collection.