Gilbert C. Din, "Empires Too Far: The Demographic Limitations of Three Imperial Powers in the Eighteenth-Century Mississippi Valley," Louisiana History (2009) 50#3 pp. 261-292 in JSTOR
A. P. Nasatir, "Anglo-Spanish Rivalry on the Upper Missouri," part 1 Mississippi Valley Historical Review (1929) 16#3 pp. 359-382, JSTOR1895064. and part 2, Mississippi Valley Historical Review (1930) 16#4 pp 507-528 JSTOR1896542