APA

American Petroleum Institute A., . (2009). Guidelines for safe work in inert confined spaces in the petroleum and petrhochemical industries. Washington: American Petroleum Institute, API.

Chicago

American Petroleum Institute API, . 2009. Guidelines for safe work in inert confined spaces in the petroleum and petrhochemical industries. Washington: American Petroleum Institute, API.

Harvard

American Petroleum Institute A., . (2009). Guidelines for safe work in inert confined spaces in the petroleum and petrhochemical industries. Washington: American Petroleum Institute, API.

MLA

American Petroleum Institute API, . Guidelines for safe work in inert confined spaces in the petroleum and petrhochemical industries. Washington: American Petroleum Institute, API. 2009.