References
- Phillips N.R. (1982): Observations on the Birds of North Yemen in 1979. – Sandgrouse 4: 37–59, Sandy.
- Porter R.F. Christensen S. (1987): The autumn migration of raptors and other soaring birds in North Yemen. – Sandgrouse 9: 121–124, Sandy.
- Porter R.F. Martins R.P Shaw K.D. Sørensen U. (1996): The status of non-passerines in southern Yemen and the records of the OSME survey in spring 1993. —Sandgrouse 17: 22–53, Sandy.
- Porter R.F. Martins R.P. Stone F. (1996): The Ornithological Society of the Middle East’s survey of south Yemen and Socotra, March-May 1993: an introduction. – Sandgrouse 17: 5–14, Sandy.
- Rands M.R.W. Porter R.F. Brooks D.J. Rands G.F. (1987): The ornithological Society of the Middle East’s expedition to North Yemen October–December 1985: an introduction. –Sandgrouse 9: 1–3, Sandy.
- Welch G.R. Welch H.J. (1988): The autumn migration of raptors and other soaring birds across the Bab-el-Mandeb Straits. – Sandgrouse 10: 26–50, Sandy.
- Welch G.R. Welch H.J. (1989): Djibouti II. Autumn ‘85. – privately published, Whittlesey, 195 PP.
- Welch G.R. Welch H.J. (1992): Djibouti III. Migrant raptor count. – privately published, Saxmundham, 123 pp.