Cita APA

Hesser, D. T., & Leach, S. S. (1989). Focus on earth science. Columbus, Ohio: Merrill.

Citación estilo Chicago

Hesser, Dale T., y Susan S. Leach. Focus On Earth Science. Columbus, Ohio: Merrill, 1989.

Cita MLA

Hesser, Dale T., y Susan S. Leach. Focus On Earth Science. Columbus, Ohio: Merrill, 1989.