Laer, T. (1936). Forty years of the most phenomenal progress in the annals of the United States and of the world: The evolution of German immigrant into an American citizen. New York: G. P. Putnam.

Laer, Theodor. Forty Years of the Most Phenomenal Progress in the Annals of the United States and of the World: The Evolution of German Immigrant Into an American Citizen. New York: G. P. Putnam, 1936.

Laer, Theodor. Forty Years of the Most Phenomenal Progress in the Annals of the United States and of the World: The Evolution of German Immigrant Into an American Citizen. New York: G. P. Putnam, 1936.