ILO 1925, p. 29. International Labour Office. "Les tués et les disparus" [The Dead and the Missing]. Enquête sur la production. Rapport général [Survey of production. General Report] (in French). Vol. 4. Part II. Paris et al.: Berger-Levrault, 1923–25. OCLC6445561.
Grebler & Winkler 1940, p. 78. Grebler, L.; Winkler, W. (1940). The Cost of the World War to Germany and to Austria-Hungary. Economic and Social History of the World War. Supplementary Volumes. New Haven, CT: Yale University Press for Carnegie Endowment for International Peace: Division of Economics and History. OCLC254453292.
Baldwin 1962, p. 27. Baldwin, Hanson (1962). World War I: An Outline History. London: Hutchinson. OCLC988365.