@inbook{12414,
  author = {Kent-Andre Mardal and Hans Langtangen},
  title = {Mixed Elements in Diffpack},
  year = {2003},
  journal = {Advanced Topics in Computational Partial Differential Equations - Numerical Methods and Diffpack Programming},
  pages = {153-198},
  publisher = {Springer},
  editor = {Hans Langtangen and Aslak Tveito},
}