Görlich, D., Kostka, S., Kraft, R., Dingwall, C., Laskey, R. A., Hartmann, E., & Prehn, S. (1995). Two different subunits of importin cooperate to recognize nuclear localization signals and bind them to the nuclear envelope. Current Biology, 5(4), 383-392. doi:10.1016/S0960-9822(95)00079-0.