Mr. Layne,
On the Compiled Military Service Record of your ancestor you received from the National Archives, the "cards" will refer to an original record that will likely be at the National Archives. You will physically have to go to the National Archives to view these. Once you are at the National Archives take that record and they can help you track the material via the reference on the card. Good Luck!
Respectfully,
Gerald D. Hodge, Jr.
War Between the States Historian
Historian: 39th Georgia Volunteer Infantry Regiment
http://39thgavolinfrgt.homestead.com/39thHomepage.html