I found three sources on the topic with a 5 min search in scholarly databases.
Wilson Quarterly; Summer98, Vol. 22 Issue 3, p127, 1/2p
Human Events; 02/11/2000, Vol. 56 Issue 5, p18, 1/2p
Journal of American History; Jun96, Vol. 83 Issue 1, p219-219, 4/5p
Previous FR threads on the topic:
An opposing view: Descendant of black Confederate soldier speaks at museum
Black Confederate veteran to get proper memorial at Blandford
Black Confederate soldiers overlooked during Black History Month
Black Confederate-flag supporter irks some on march to Texas
Black Confederates
Black man supports Confederate flag in march
Black Man Was a Rock Hill Leader Before Integration (Belonged to KKK? a redshirt? in 1870s SC
Black service, on both sides, in the Civil War
Blacks join Confederate Army heritage group
Blacks, Jews Fight on Side of the South
Former Slave's Family Sees Him Honored At Last (Chris Columbus in Florida)
Confederate group, blacks to clean up cemetery [NC] - more comments
Did free blacks support the Confederacy during the Civil War? Novel on blacks in Confederate South
DIXIE'S CENSORED SUBJECT BLACK SLAVEOWNERS
Minorities During the War Between the States: Collected Resources
Natchez(Ms)conference explores Free Blacks in the Antebellum South (Imagine That)
Ohatchee marker to have names of black and white Confederate vets
Quotations on Black Confederates
UDC marks another black Confederate grave (pt1)
UDC marks another black Confederate grave (pt2)
Not to mention a surprising wealth of “dead-tree” references to blacks participating in the Civil War on both sides, with some dating back to Reconstruction (many of which now out of print).
Sigh. You know better. When I say there are three or four or whatever number of scholars who say “x,” I certainly don’t mean that there are ONLY that number. I’m not here to do historiography, merely to make a few suggestions. But feel free to post all the lists you want.