Cita APA (7a ed.)

Friend, S. (2000). Shaping the earth erosion. Twenty-First Century Books.

Cita Chicago Style (17a ed.)

Friend, Sandra. Shaping the Earth Erosion. Brookfield, Conn.: Twenty-First Century Books, 2000.

Cita MLA (9a ed.)

Friend, Sandra. Shaping the Earth Erosion. Twenty-First Century Books, 2000.