Preston, R. J. (1968). Rocky mountain trees: A handbook of the native species with plates and distributions maps (3a. ed.). Dover.
Cita Chicago (17th ed.)Preston, Richard J. Rocky Mountain Trees: A Handbook of the Native Species with Plates and Distributions Maps. 3a. ed. Nueva York: Dover, 1968.
Cita MLA (9th ed.)Preston, Richard J. Rocky Mountain Trees: A Handbook of the Native Species with Plates and Distributions Maps. 3a. ed. Dover, 1968.
Atenció: Aquestes cites poden no estar 100% correctes.