WORCESTER, P. G. (1964). A textbook of geomorphology.-- 2nd ed. D. Van Nostrand.

WORCESTER, Philip G. A Textbook of Geomorphology.-- 2nd Ed. New Jersey: D. Van Nostrand, 1964.

WORCESTER, Philip G. A Textbook of Geomorphology.-- 2nd Ed. D. Van Nostrand, 1964.