@Article{SCI:Ste2008b,
  author =    "M. Steffen and R.M. Kirby and M. Berzins",
  title =     "Analysis and Reduction of Quadrature Errors in the
              Material Point Method ({MPM})",
  journal =   "International Journal for Numerical Methods in
              Engineering",
  volume =    "76",
  number =    "6",
  pages =     "922--948",
  year =      "2008",
  doi =       "10.1002/nme.2360",
  keywords =  "material point method MPM, quadrature error, error
              analysis",
  url =       "http://www.sci.utah.edu/publications/Ste2008b/steffen_08_IJNME_mpm_preprint.pdf",
}