Before revision: <ref> (Review) Oral poetry and Somali nationalism: the case of Sayyid Mahammad 'Abdille Hasan (1982) by John William Johnson pg 601 - Research in African Literatures, 1984</ref> Enrico Cerulli and Mohamed Diriye Abdullahi in their respective works Somalia: scritti vari editi ed inediti (1957) and Culture and Customs of Somalia (2001) have also summarized the origins and ethnogenesis of the Somali people.
After revision: (Review) Oral poetry and Somali nationalism: the case of Sayyid Mahammad 'Abdille Hasan (1982) by John William Johnson pg 601 - Research in African Literatures, 1984</ref> Enrico Cerulli and Mohamed Diriye Abdullahi in their respective works Somalia: scritti vari editi ed inediti (1957) and Culture and Customs of Somalia (2001) have also summarized the origins and ethnogenesis of the Somali people.