Parfitt, S.A., R.W. Barendregt, M. Breda, I. Candy, M. J. Collins, G. R. Coope, P. Durbidge, M. H. Field, J. R. Lee, A.M. Lister, R. Mutch, K.E.H. Penkman, R.C. Preece, J. Rose, C.B. Stringer, R. Symmons, J.E. Whittaker, J.J. Wymer, and A.J. Stuart. 2005. The earliest record of human activity in northern Europe. Nature, 438: 1008-1012.