The vexed question of the boundaries of Louisiana is elucidated by Henry Adams in volumes II and III of his "History of the United States." Among the more recent studies should be mentioned the articles contributed by Isaac J. Cox to volumes VI and X of the "Quarterly" of the Texas State Historical Association, and an article entitled "Was Texas Included in the Louisiana Purchase?" by John R. Ficklen in the "Publications" of the Southern History Association, vol. V. In the first two chapters of his "History of the Western Boundary of the Louisiana Purchase" (1914), T. M. Marshall has given a resume of the boundary question. Jefferson brought together the information which he possessed in "An Examination into the boundaries of Louisiana," which was first published in 1803 and which has been reprinted by the American Philosophical Society in "Documents relating to the Purchase and Exploration of Louisiana" (1904). I. J. Cox has made an important contribution by his book on "The Early Exploration of Louisiana" (1906). The constitutional questions involved in the purchase and organization of Louisiana are reviewed at length by E. S. Brown in "The Constitutional History of the Louisiana Purchase, 1803-1812" (1920).