I would start with Goggle searches, i.e., 25th Tennessee Infantry, etc.

Carol Botteron's Civil War Unit Files contains lists of contacts (experts?) on many units at:

http://sunsite.utk.edu/civil-war/unit5.html

And then, try the US Army Military History Institute, Carlisle Barracks, click on CW Unit Bibliography's

http://www.ahco.army.mil/site/finding_aids_brief.jsp

Also, If there is a National Military History Park at Cornith, the Park Historian may some of these documents in their unit files.

George Martin