All Sources

American Protective League (1917–1919). Correspondence with Field Offices. Series A1 12. Textual records. NAID: 581149 Record Group 65: Records of the Federal Bureau of Investigation, 1896-2008. The National Archives at College Park, Maryland.

American Protective League (1917–1919). Correspondence on Investigations, 1918–1919. Series A1 15. Textual records. NAID: 597893 Record Group 65: Records of the Federal Bureau of Investigation, 1896-2008. The National Archives at College Park, Maryland.