Cita APA (7th ed.)

Spellenberg, R., Earle, C. J., Nelson, G., More, D., & Hughes, A. K. (2014). Trees of Western North America. Princeton University Press.

Cita Chicago (17th ed.)

Spellenberg, Richard, Christopher J. Earle, Gil Nelson, David More, i Amy K. Hughes. Trees of Western North America. Princeton, New Jersey: Princeton University Press, 2014.

Cita MLA (9th ed.)

Spellenberg, Richard, et al. Trees of Western North America. Princeton University Press, 2014.