Good sources. Hmmm I haven't been asked that in a while

Some are and not certainly not limited to...

Johnny Reb the Uniform of the Confederate Army, 1861-1865, by Leslie D. Jensen.*
Echoes of Glory Arms and Equipment of the Confederacy Time Life Books *
Brassey's History of Uniforms American Civil War Confederate Army by Ron Field *
Osprey Military....too many to mention.

Photographs...Any books on 19th Century Daguerreotype, Tintype, Ambrotype techniques and history. Study, study, study.
Diaries, manuscripts and the Official Records are great sources for material identifications and uses.

Go visit the Confederate Museum in New Orleans. They have the greatest collection of authentic uniforms, in near perfect condition, anywhere I have seen, or any museums that exhibit uniforms.

My favorites*