Cita APA (7a ed.)
Ehret, W. F. (1942). Physical science. The Macmillan company.
Cita Chicago Style (17a ed.)
Ehret, William Frederick. Physical Science. New York: The Macmillan company, 1942.
Cita MLA (9a ed.)
Ehret, William Frederick. Physical Science. The Macmillan company, 1942.
Precaución: Estas citas no son 100% exactas.