@article{RattanaBoeckmann2013,
  author    = {Amornrat Rattana and Christine B{\"o}ckmann},
  title     = {Matrix methods for computing eigenvalues of Sturm-Liouville problems of order four},
  journal   = {Journal of computational and applied mathematics},
  volume    = {249},
  number    = {8},
  pages     = {144 -- 156},
  doi       = {10.1016/j.cam.2013.02.024},
  year      = {2013},
}