David A. Wolff, Industrializing the Rockies: Growth, Competition, and Turmoil in the Coalfields of Colorado and Wyoming, 1868-1914 (Boulder: Univ. of Colorado Press, 2003), 5-6, 21-22.
H.K. Thomas, Diary, April 4, 1871. September 2, 1871.
H.K. Thomas, Diary, Oct. 17, 1870.
H.K. Thomas, Diary, Oct, 26, Oct. 27, 1870.
H.K. Thomas, Diary, Jan. 27, 1871.