@Article{WBR09,
  author = 	 {Yaqi Wang and Wolfgang Bangerth and Jean Ragusa},
  title = 	 {Three-dimensional $h$-adaptivity for the multigroup
                  neutron diffusion equations},
  journal = 	 {Progr. Nucl. Energy},
  year = 	 2009,
  volume = 	 51,
  pages = 	 {543--555}}