United States. Bureau of Entomology and Plant Quarantine. (1939). Modification of Dutch elm disease quarantine regulations. [s.n.].
Chicago Style (17th ed.) CitationUnited States. Bureau of Entomology and Plant Quarantine. Modification of Dutch Elm Disease Quarantine Regulations. [Washington]: [s.n.], 1939.
MLA (9th ed.) CitationUnited States. Bureau of Entomology and Plant Quarantine. Modification of Dutch Elm Disease Quarantine Regulations. [s.n.], 1939.
Warning: These citations may not always be 100% accurate.