Chemical Warfare Service - Drills - Masks - This picture illustrates the respiratory drill which is held behind the British lines every time a company leaves for the trenches. The proper use and adjustment is demonstrated in this drill as its purpose is to prevent suffering in the enemy's gas attacks.

Chicago citation style
War Department. 1789-9/18/1947. Chemical Warfare Service - Drills - Masks - This picture illustrates the respiratory drill which is held behind the British lines every time a company leaves for the trenches. The proper use and adjustment is demonstrated in this drill as its purpose is to prevent suffering in the enemy's gas attacks.. 1917-01-01/1918-12-31. Retrieved from the Digital Public Library of America, http://catalog.archives.gov/id/26424012. (Accessed May 20, 2018.)
APA citation style
War Department. 1789-9/18/1947, (1917-01-01/1918-12-31) Chemical Warfare Service - Drills - Masks - This picture illustrates the respiratory drill which is held behind the British lines every time a company leaves for the trenches. The proper use and adjustment is demonstrated in this drill as its purpose is to prevent suffering in the enemy's gas attacks.. Retrieved from the Digital Public Library of America, http://catalog.archives.gov/id/26424012
MLA citation style
War Department. 1789-9/18/1947. Retrieved from the Digital Public Library of America <http://catalog.archives.gov/id/26424012>.
Note: These citations are programmatically generated and may be incomplete.