Cita APA (7a ed.)

KREBS, R. D., & WALKER, R. D. (1971). Highway materials. McGraw-Hill.

Cita Chicago Style (17a ed.)

KREBS, Robert D., y Richard D. WALKER. Highway Materials. New York: McGraw-Hill, 1971.

Cita MLA (9a ed.)

KREBS, Robert D., y Richard D. WALKER. Highway Materials. McGraw-Hill, 1971.