Molecular tectonic model of virus structural transitions: the putative cell entry states of poliovirus - Belnap, DM; Filman, DJ; Trus, BL; Cheng, NQ; Booy, FP; Conway, JF; Curry, S; Hiremath, CN; Tsang, SK; Steven, AC; Hogle, JM (JOURNAL OF VIROLOGY, 2000)