APA

Saaty T. L., . (1977). The four-color problem. New York: McGraw-Hill.

Chicago

Saaty Thomas L, . 1977. The four-color problem. New York: McGraw-Hill.

Harvard

Saaty T. L., . (1977). The four-color problem. New York: McGraw-Hill.

MLA

Saaty Thomas L, . The four-color problem. New York: McGraw-Hill. 1977.