Citazione Stile APA (7a Edizione)

Willoughby, D. A. (2005). Horizontal directional drilling: Utility and pipeline applications (First edition.). McGraw-Hill.

Citazione stile Chigago Style (17a edizione)

Willoughby, David A. Horizontal Directional Drilling: Utility and Pipeline Applications. First edition. New York: McGraw-Hill, 2005.

Citatione MLA (9a ed.)

Willoughby, David A. Horizontal Directional Drilling: Utility and Pipeline Applications. First edition. McGraw-Hill, 2005.