For a long time, Terry L. Jones's Lee's Tigers (1987) has been the standard study of the Louisiana contribution to the manpower of the Army of Northern Virginia. It was certainly groundbreaking at the time and was also reissued in paperback format in 2002. From the description: "Lee's Tigers is the first study to utilize letters, diaries, and muster rolls to provide a detailed account of the origins, enrollments, casualties, and desertion rates of these soldiers. Jones supplies the first major work to focus solely on Louisiana's infantry in Lee's army throughout the course of the war."
Jones himself remains active on message boards, both dispensing knowledge and soliciting information. The result of his sustained research and curiosity is a brand new book Lee's Tigers Revisited: The Louisiana Infantry in the Army of Northern Virginia (LSU, Sept 2017). It "dramatically expands and revises his acclaimed history of the approximately 12,000 Louisiana infantrymen who fought in Robert E. Lee’s Army of Northern Virginia." If simple page count (296 in the paperback reprint vs. 544 in Revisited) is an accurate representation of such things, dramatic expansion in the new edition appears to be no exaggeration.