Ziefert, H., & Bolam, E. (1998). A polar bear can swim: What animals can and cannot do. Viking.
Cita Chicago Style (17a ed.)Ziefert, Harriet, y Emily Bolam. A Polar Bear Can Swim: What Animals Can and Cannot Do. New York: Viking, 1998.
Cita MLA (8a ed.)Ziefert, Harriet, y Emily Bolam. A Polar Bear Can Swim: What Animals Can and Cannot Do. Viking, 1998.
Precaución: Estas citas no son 100% exactas.