The Confederate agents' correspondence, both official and private, will be much used later in this work and here requires explanation.

But four historical works of importance deal with it extensively, (1) Richardson, _Messages and Papers of the Confederacy_, 2 vols., 1905, purports to include the despatches of Mason and Slidell to Richmond, but is very unsatisfactory.
Important despatches are missing, and elisions sometimes occur without indication.

(2) Virginia Mason, _The Public Life and Diplomatic Correspondence of James M.Mason_, 1906, contains most of Mason's despatches, including some not given by Richardson.

The author also used the _Mason Papers_ (see below).

(3) Callahan, _The Diplomatic History of the Southern Confederacy_, 1901, is the most complete and authoritative work on Southern diplomacy yet published.