I recommend these books:
East Tennessee in the Civil War by O P Temple
Tennessee's War by Stanly Horn
History of the 1st Tennessee Cavalry by W R Carter
Porter Alexander's Memior (I don't recall the title)
Longstreet's Book
The University of Tenneesse, and the McClung Collection both in Knoxville can provide less well known local diaries as can the Morristown, Rogersville, Greenville, libraries.
Try Tusculum College and the Andrew Johnson historical site,in Greenville as well as the East Tennessee State University in Johnson City. Good Luck!