APA
American Petroleum Institute A., . (1999). Recommended practice for occupational safety for oil and gas well drilling and servicing operations. 54. 3rd ed. Washington: American Petroleum Institute, API.
Chicago
American Petroleum Institute API, . 1999. Recommended practice for occupational safety for oil and gas well drilling and servicing operations. 54. 3rd ed. Washington: American Petroleum Institute, API.
Harvard
American Petroleum Institute A., . (1999). Recommended practice for occupational safety for oil and gas well drilling and servicing operations. 54. 3rd ed. Washington: American Petroleum Institute, API.
MLA
American Petroleum Institute API, . Recommended practice for occupational safety for oil and gas well drilling and servicing operations. 54. 3rd ed. Washington: American Petroleum Institute, API. 1999.