↑Priest, J. (1834). American antiquities, and discoveries in the West: being an exhibition of the evidence that an ancient population of partially civilized nations, differing entirely from those of the present Indians, peopled America many centuries before its discovery by Columbus, and inquiries into their origin, with a copious description of many of their stupendous works, now in ruins; with conjectures concerning what may have become of them; compiled from travels, authentic sources, and the researches of antiquarian societies. Albany: Printed by Hoffman & White
↑The Origin and Development of the Cuneiform System of Writing, Samuel Noah Kramer, Thirty Nine Firsts In Recorded History, pp 381—383
↑Clare, I. S. (1906). Library of universal history: containing a record of the human race from the earliest historical period to the present time; embracing a general survey of the progress of mankind in national and social life, civil government, religion, literature, science and art. New York: Union Book. Page 1519 (cf., Ancient history, as we have already seen, ended with the fall of the Western Roman Empire; […])
↑United Center for Research and Training in History. (1973). Bulgarian historical review. Sofia: Pub. House of the Bulgarian Academy of Sciences. Page 43. (cf. … in the history of Western Europe, which marks both the end of ancient history and the beginning of the Middle Ages, is the fall of the Western Empire.)
↑Robinson, C. A. (1951). Ancient history from prehistoric times to the death of Justinian. New York: Macmillan.