Z. Yang, B. Zhang, J. Lei, and T. Dang. Nonlinear Response of the Cross Polar Cap Potential to Solar Wind Density Under Northward Interplanetary Magnetic Field. Geophysical Research Letters, volume 47, issue 8, 2020 . D. Lin, B. Zhang, W. A. Scales, M. Wiltberger, C. R. Clauer, and Z. Xu. The role of solar wind density in cross polar cap potential saturation under northward interplanetary magnetic field. Geophysical Research Letters, American Geophysical Union, volume 44, pages 11729-11734, 2017 . K. A. Lynch, D. Hampton, M. Mella, B. Zhang, H. Dahlgren, M. Disbrow, P. M. Kintner, M. Lessard, E. Lundberg, and H. C. Stenbaek-Nielsen. Structure and dynamics of the nightside poleward boundary: Sounding rocket and ground-based observations of auroral electron precipitation in a rayed curtain. J. Geophys. Res., volume 117, 2012 .