That is the Army folks talking about their very extensive photo library at their Carlisle Barracks, Pa. facility which include
photos of members of the 31st Virginia.

The U. S. Army Military History Institute, Carlisle Barracks, Penn., lists the following documents in their Unit Bibliography

USAMHI
HistServices
16 May 03

31st Virginia Infantry Regiment

.......

Our Photo Archive includes images of individuals of this unit.

The following pertinent personal papers are in the Institute's Manuscript Archive:

Bosworth, John W. HCWRTColl GACColl

Hall, James E. (Diary) BrakeColl

Whitley, John B. HCWRTColl GACColl