Birbirso, Dereje Tadesse, and Tesfaye Gudeta Gerba. “Questioning the Origin of Indo-European: A Comparative Evolutionary Analysis of Hittite and Cushitic (Oromo)”. International Journal of Sciences: Basic and Applied Research (IJSBAR), vol. 19, no. 2, Jan. 2015, pp. 250-8, https://gssrr.org/JournalOfBasicAndApplied/article/view/3181.