1. Marco Polo, in The Description of the World, edited by A C Motile and P Pelliot, G. Routledge, London, 1938. Available online; see Ref.
2. C M Doughty, Travels in Arabia Deserta, volume~l, Cambridge University Press, Cambridge, 1888.
3. R A Bagnold, The Physics of Blown Sand and Desert Dunes, Chapman and Hall, London, 1941.
4. G N Curzon, Tales of Travel, Hodder and Stoughton, London, 1923 (reprinted: Century, London, 1988).
5. K Pye and H Tsoar, Aeolian Sand and Sand Dunes, Unwin Hyman, London, 1990