Genome-wide association studies identify four ER negative-specific breast cancer risk loci - Garcia-Closas, Montserrat; Chang-Claude, Jenny; Burwinkel, Barbara; Brenner, Hermann; Hamann, Ute; Marmé, Frederik; Schneeweiss, Andreas; Sohn, Christof; Müller, Heiko; Arndt, Volker; Hein, Rebecca; Kaaks, Rudolf; et al. (Nature genetics, 2013)