History of the United States,
by Charles A. Beard and Mary R. Beard.

APA Citation

Beard, C. A. (Charles Austin)., Beard, M. Ritter. (1950). History of the United States. Rev. ed. New York: The Macmillan company.

MLA Citation

Beard, Charles A. (Charles Austin), 1874-1948, and Mary Ritter Beard. History of the United States. Rev. ed. New York: The Macmillan company, 1950.