1. Andrews, C.: Egyptian Mummies. London: British Museum 1984
2. Nissenbaum, A.: Bull. Am. Assoc. Pet. Geol. 62, 837 (1978)
3. Harrison, R. G., Abdalla, A. B.: Antiquity 46, 8 (1972)
4. Lucas, A.: Ancient Egyptian Materials and Industries, p. 303. London: Arnold 1962
5. Abraham, H.: Asphalts and Allied Substances, Vol. 1, p. 3. New York: van Nostrand 1960