Cita APA (7th ed.)
Abul-Haggag, Y. (1961). A Contribution to the physiography of northern Ethiopia. Athlone Press.
Cita Chicago (17th ed.)
Abul-Haggag, Y. A Contribution to the Physiography of Northern Ethiopia. London: Athlone Press, 1961.
Cita MLA (9th ed.)
Abul-Haggag, Y. A Contribution to the Physiography of Northern Ethiopia. Athlone Press, 1961.
Atenció: Aquestes cites poden no estar 100% correctes.