I have an ancestor who was in Co. C. 40th Ga. Inf. I have some military records (3 items) and on one of the cards which is labeled a "Reference Card" is this reference:

"See Manuscript No. 1999 page 28"

Died

Dated - April 25 1864

Can someone tell me what the Manuscript 1999 is and/or how to access it? There is not very much information on any of the cards.
Thanks.