@Article{SCI:Gri2016a,
  author =    "C. Gritton and M. Berzins",
  title =     "Improving accuracy in the MPM method using a null
              space filter",
  journal =   "Computational Particle Mechanics",
  pages =     "1--12",
  year =      "2016",
  issn =      "2196-4386",
  doi =       "10.1007/s40571-016-0134-3",
  url =       "http://www.sci.utah.edu/publications/Gri2016a/mpmpaper.pdf",
}