Kaufmann, PR, Fundel, F, Fischer, H, Bigler, M, Ruth, U, Udisti, R, Hansson, ME, de Angelis, M, Barbante, C, Wolff, EW, Hutterli, MA and Wagenbach, D (2010) Ammonium and non-sea salt sulfate in the EPICA ice cores as indicator of biological activity in the Southern Ocean. Quaternary Science Reviews, 29(1-2). 313-323. doi:10.1016/j.quascirev.2009.11.009