Lipsky et al. 1964, p. 608. Lipsky, George A.; Barnett, Clifford R.; Blanchard, Wendell; Hirsch, Abraham M.; Maday, Bela C.; Teleki, Suzanne (1964). "Section IV: Military Background". U.S. Army Area Handbook for Ethiopia (2nd ed.). Washington DC.: American University, for U.S. Govt. Printing Office. Retrieved 21 December 2021.
Lipsky et al. 1964, pp. 608–9. Lipsky, George A.; Barnett, Clifford R.; Blanchard, Wendell; Hirsch, Abraham M.; Maday, Bela C.; Teleki, Suzanne (1964). "Section IV: Military Background". U.S. Army Area Handbook for Ethiopia (2nd ed.). Washington DC.: American University, for U.S. Govt. Printing Office. Retrieved 21 December 2021.