United States. Department of Agriculture, United States. National Archives and Records Service, Willits, M., Dabney, C. W., Brigham, J. H., Hays, W. M., . . . Vrooman, C. S. (1947). Letters sent by the assistant secretaries of agriculture, 1889-1919. National Archives.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रUnited States. Department of Agriculture, United States. National Archives and Records Service, Mr Willits, Charles William Dabney, Joseph H. Brigham, W. M. Hays, B. T. Galloway, और Carl Schurz Vrooman. Letters Sent by the Assistant Secretaries of Agriculture, 1889-1919. Washington, [D.C.]: National Archives, 1947.
एमएलए (8वां संस्करण) प्रशस्ति पत्रUnited States. Department of Agriculture, et al. Letters Sent by the Assistant Secretaries of Agriculture, 1889-1919. National Archives, 1947.