Boyle, Peter G. The Study of an Isolationist: Hiram Johnson. Ph.D. dissertation, University of California, Los Angeles, 1970.
Burke, Robert E. A Friendship in Adversity: Burton K. Wheeler and Hiram W. Johnson. Montana 36 (Winter 1986): 12-25.
___. Hiram Johnsons Impressions of William E. Borah. Idaho Yesterdays 17 (Spring 1973): 2-11.
___. The Political Oratory of Hiram Johnson. Journal of the West 27 (April 1988): 20-27.
___, ed. The Diary Letters of Hiram Johnson, 1917-1945. 7 vols. New York: Garland Publishing, 1983.
Cain, Earl R. Hiram Johnson: Irreconcilable Isolationist. In Landmarks in Western Oratory, edited by David H. Grover, pp. 145-57. University of Wyoming Publications, vol. 34, nos. 1-10, August 7, 1968. Laramie: Graduate School, University of Wyoming, 1968.
Davenport, Frederick M. Did Hughes Snub Johnson?An Inside Story. American Political Science Review 43 (April 1949): 321-32.
DeWitt, Howard A. Hiram Johnson and Early New Deal Diplomacy, 1933-1934. California Historical Quarterly 53 (Winter 1974): 377-86.
___. Hiram Johnson and World War I: A Progressive in Transition. Southern California Quarterly 56 (Fall 1974): 295-305.
___. Hiram W. Johnson and American Foreign Policy, 1917-1941. Ph.D. dissertation, University of Arizona, 1972.
___. Hiram W. Johnson and Economic Opposition to Wilsonian Diplomacy: A Note. Pacific Historian 19 (Spring 1975): 15-23.
___. The New Harding and American Foreign Policy: Warren G. Harding, Hiram W. Johnson, and Pragmatic Diplomacy. Ohio History 86 (Spring l977): 96-114.
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Fitzpatrick, John James, III. Senator Hiram W. Johnson: A Life History, 1866-1945. Ph.D. dissertation, University of California, Berkeley, 1975.
Greenbaum, Fred. Hiram Johnson and the New Deal. Pacific Historian 18 (Fall 1974): 20-35.
Hamilton, Marty. Bull Moose Plays an Encore: Hiram Johnson and the Presidential Campaign of 1932. California Historical Society Quarterly 41 (September 1962): 211-21.
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Lincoln, A. My Dear Friend and Champion: Letters Between Theodore Roosevelt and Hiram Johnson in 1918. California Historical Society Quarterly 68 (March 1969): 19-36.
___. My Dear Governor: Letters Exchanged by Theodore Roosevelt and Hiram Johnson. California Historical Society Quarterly 38 (September 1959): 229-47.
___. My Dear Senator: Letters Between Theodore Roosevelt and Hiram Johnson in 1917. California Historical Society Quarterly 42 (September 1963): 221-39.
___. Theodore Roosevelt, Hiram Johnson, and the Vice-presidential Nomination of 1912. Pacific Historical Review 28 (August 1959): 267-83.
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___. Hiram Johnson: The Making of an Irreconcilable. Pacific Historical Review 41 (November 1972): 505-26.
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___. Hiram Johnson, the California Progressives and the Hughes Campaign of 1916. Pacific Historical Review 31 (November 1962): 403-12.
___. Hiram Johnson, The Lincoln-Roosevelt League, and the Election of 1910. California Historical Society Quarterly 45 (September 1966): 225-40.
U.S. Congress. Memorial Services Held in the House of Representatives and Senate of the United States: Together with Remarks Presented in Eulogy of Hiram Warren Johnson, Late Senator from California. 79th Cong., 2d sess., 1946. Washington: Government Printing Office, 1948.
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___. Hiram Johnson: Political Revivalist. Lanham, MD: University Press of America, 1995.