CPH to Stanford, Sept. 27, 1872, Huntington Letters, 3:357.
CPH to Hopkins, Jan. 3, 1873, LB, 3:93, box 21, Hopkins Collection.
Cohen to Ralston, Jan. 4, 1873, LB, 12:19, Hopkins to Ralston, Jan. 6, 1873, LB, 12:21, Ralston to Hopkins, Jan. 6, 1873, LB, 12:25, Hopkins to Ralston, Jan. 8, 1873, all in box 25, Hopkins Collection.
CPH to Hopkins, March 10, 1870, LB, 2:96, CPH to Hopkins, March 19, 1873, LB, 4: 27, box 21, Hopkins Collection.
CPH to Hopkins, Feb. 27, 1873, LB, 3:141, box 21, Hopkins Collection.