Bender, M. L. 1975. Omotic: a new Afroasiatic language family. (University Museum Series, 3.) Carbondale, IL: Southern Illinois University.
Blench, Roger. 2006. Archaeology, Language, and the African Past. AltaMira Press
Hayward, Richard J., ed. 1990. Omotic Language Studies. London: School of Oriental and African Studies.
Hayward, Richard J. 2003. Omotic: the "empty quarter" of Afroasiatic linguistics. In Research in Afroasiatic Grammar II: selected papers from the fifth conference on Afroasiatic languages, Paris 2000, ed. by Jacqueline Lecarme, pp. 241–261. Amsterdam: John Benjamins.
Lamberti, Marcello. 1991. Cushitic and its classification. Anthropos 86(4/6):552-561.
Zaborski, Andrzej. 1986. Can Omotic be reclassified as West Cushitic? In Gideon Goldenberg, ed., Ethiopian Studies: Proceedings of the 6th International Conference, pp. 525–530. Rotterdam: Balkema.
I. M. Diakonoff (1998) Journal of Semitic Studies 43:209: "It is quite evident that cultural ties between Proto-Semitic and the African branches of the Afrasian macrofamily must have been severed at a very early date indeed. However, the grammatical structure of [Common Semitic] (especially in the verb) is obviously close to that of Common Berbero-Libyan (CBL), as well as to Bedauye. (Bedauye might, quite possibly, be classified as a family distinct from the rest of Kushitic.) The same grammatical isoglosses are somewhat more feebly felt between Semitic and (the other?) Kushitic languages. They practically disappear between the Semitic and the Omotic languages, which were formerly termed Western Kushitic, but which actually may not be Afrasian at all, like their neighbours the Nubian languages and Meroitic."
Rolf Theil (2006) Is Omotic Afro-Asiatic? pp 1–2: "I claim to show that no convincing arguments have been presented [for the inclusion of Omotic (OM) in Afro-Asiatic (AA)], and that OM should be regarded as an independent language family. No closer genetic relations have been demonstrated between OM and AA than between OM and any other language family."
^Gerrit Dimmendaal (2008) "Language Ecology and Linguistic Diversity on the African Continent", in Language and Linguistics Compass 2/5:841: "Although its Afroasiatic affiliation has been disputed, the allocation of Omotic within this family is now well-established, based on the attestation of morphological properties that this family shares with other Afroasiatic branches."