Don't know if you have these, but here are the holding of the U.S. Army Military History Institute, Carlisle Barracks, Pa. found in their unit bibliography

U.S. Army Military History Institute 950 Soldiers Drive
Carlisle Barracks, PA 17013-5021 1 May 2012

2nd Colorado Cavalry Regiment

Curtis, Samuel S. A Cruise on the Benton: A Narrative of Combat on the Missouri River in the Civil War. Waynesboro, VA: M&R Books, 1967. 17 p.

Dyer, Frederick H. A Compendium of the War of the Rebellion. Vol. 2. Dayton, OH: Morningside, 1979. pp. 1004-05. (Concise summary of the regiment's service).

Mahan, Don M. Muskets and Bayonets: The Story of James B. Wasson, Company “B” and the Second Colorado Volunteer Cavalry in the Civil War, 1861-1865. [Edited by Carole M. Wilcox] Phoenix, AZ: Western History, 2011. 249 p.

Nankivell, John H. History of the Military Organizations of the State of Colorado, 1860-1935. Denver: Kistler, 1935. pp. 21-25. UA100.N3.

Williams, Ellen. Three Years and a Half in the Army: Or, History of the Second Colorados. NY: Fowler & Wells, 1885. 178 p.

The Institute's Photographic Archive includes images of the unit.

See also the following pertinent personal papers in the Institute's Archives:

Conley, Thomas - CWDocColl (Regimental newsletter, Soldier's Letter, #s 1-50, Aug 1864- Nov 1865; newspaper clippings, Jul 27, 1864-Apr 27, 1887)

Graham, John S. (In the Graham Family Papers)-CWDocColl (Enlisted man's letters, Mar 27, 1863 & Mar 24, 1864)

McGrew, Levi - CWDocColl (Enlisted man's letters, Feb 1, 1864-Jan 27, 1865; also regimental newsletter Soldier's Letter, Aug, 1864-Jun 17, 1865)