APA استشهاد

Spencer, E. W. (1969). Introduction to the structure of the earth. McGraw-Hill.

استشهاد بنمط شيكاغو

Spencer, Edgar W. Introduction to the Structure of the Earth. New York: McGraw-Hill, 1969.

MLA استشهاد

Spencer, Edgar W. Introduction to the Structure of the Earth. McGraw-Hill, 1969.