Thanks, George. I did not want to confuse her with the other books as they did not cover the subject she was interested in, the 3rd Company, as well as "In Camp and Battle" does. Cannoneers in Gray; the article by Larter; The Pride of the Confederate Artillery; and A Confederate Artilleryman at Shiloh all deal with the 5th Company which served in an entire different theater of war (as does Powell Casey's " An Outline of the of the Civil War Campaigns and Engagements of the Washington Artillery" which was not noted in the list). Henry Baker's book covers the 4th Company only.
Art Bergeron's book lists an brief overview of all Louisiana units and Booth's books are service records of the entire state. Confederate Military History does not contain much, nor does Units in the Confederate States Army. The By-laws were for the Washington Artillery at the end of the century (They still exist today as the 141st Field Artillery of the Louisiana National Guard and are currently stationed in Iraq.)
I have not read the remaining two you suggested but the Southern Historical Society Papers one looks like a very short article. The other seems more lengthy but with 'documents' doesn't seem to be an organized history.