1. u. : Report of the Mission to Lake Tana 1920–21, Cairo 1925.
2. : Resultati scientiffici di un viaggio nella Colonia Eritrea, Florenz 1912, p. 65.
3. : The Riftvalleys, London 1921, p. 338.
4. : Geology and Zoology of Abyssinia, London 1870, p. 182.
5. : Physiography of the River Nile, Cairo 1906, p. 184