National Safety Council. (1956). Supervisors safety manual; better production without injury and waste from accidents. s.n.
Citazione stile Chigago Style (17a edizione)National Safety Council. Supervisors Safety Manual; Better Production Without Injury and Waste from Accidents. Chicago: s.n, 1956.
Citatione MLA (9a ed.)National Safety Council. Supervisors Safety Manual; Better Production Without Injury and Waste from Accidents. s.n, 1956.
Attenzione: Queste citazioni potrebbero non essere precise al 100%.