Proceedings of the National Academy of Sciences of the United States of America

Bettencourt, L., J. Lobo, D. Helbing, Chr. Kühnert and G.B. West (2007). ‘Growth, innovation, scaling, and the pace of life in cities’. PNAS 104.17: 7301–7306.
Turchin, P. and W. Scheidel (2009). ‘Coin hoards speak of population declines in Ancient Rome’. PNAS 106.41: 17276–17279.
McConnell, J, A. Wilson, M. Arienzo, N. Chellman, S. Eckhardt, E. Thompson, M. Pollard and J. Steffensen (2018). ‘Lead pollution recorded in Greenland ice indicates European emissions tracked plagues, wars, and imperial expansion during antiquity’. PNAS 115.22: 5726–5731.