After the fall: Late-time spectroscopy of type IIP supernovae

Jeffrey M. Silverman, Stephanie Pickett, J. Craig Wheeler, Alexei V. Filippenko, József Vinkó, G. H. Marion, S. Bradley Cenko, Ryan Chornock, Kelsey I. Clubb, Ryan J. Foley, Melissa L. Graham, Patrick L. Kelly, Thomas Matheson, Joseph C. Shields