1. Agricola G (1556), De Re Metallica, Translated from the first Latin edition of 1556 by HC Hoover and LH Hoover (1950), Dover Publications, Inc., New York.
2. Connan J (1999), Use and trade of bitumen in antiquity and prehistory: molecular archaeology reveals secrets of past civilizations, Philos. Trans. R. Soc. London, Ser. B 354, 33–59.
3. Boe¨da E , Connan J, Dessort D, Muhesen S, Mercier N, Valladas H, and Tisne´rat N (1996), Bitumen as a hafting material on middle palaeolithic artefacts, Nature (London) 380, 336–338.
4. Boe¨da E, Connan J, and Muhesen S (1998), Bitumen as a hafting material on middle palaeolithic artifacts from the El Kowm, Basin, Syria, Neandertals and Modern Humans in Western Asia, T Akazawa, K Aoki, and O Bar-Yosef (eds), Plenum Press, New York and London.
5. Childe VG (1971), Progress and Archaeology, Greenwood Press, Connecticut.