Não informado. (1959). Bulletin of the Geophysical Observatory. Haile Selassie i University.
Chicago (17e ed.) BronvermeldingNão informado. Bulletin of the Geophysical Observatory. Addis Ababa: Haile Selassie i University, 1959.
MLA (8e ed.) BronvermeldingNão informado. Bulletin of the Geophysical Observatory. Haile Selassie i University, 1959.
Let op: Deze citaties zijn niet altijd 100% accuraat.