Dyfyniad APA

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

Dyfyniad Arddull Chicago

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

Dyfyniad MLA

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

Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.