.. [petsc-www] PETSc Web page. Satish Balay, Kris Buschelman,
   William D. Gropp, Dinesh Kaushik, Matthew G. Knepley, Lois Curfman
   McInnes, Barry F. Smith and Hong
   Zhang. http://www.mcs.anl.gov/petsc. 2001.

.. [petsc-user-ref] Satish Balay, Kris Buschelman, Victor Eijkhout,
   William D. Gropp, Dinesh Kaushik, Matthew G. Knepley, Lois Curfman
   McInnes, Barry F. Smith and Hong Zhang. PETSc Users
   Manual. ANL-95/11 - Revision 2.1.5. Argonne National
   Laboratory. 2004

.. [petsc-efficient] Satish Balay, Victor Eijkhout, William D. Gropp,
   Lois Curfman McInnes and Barry F. Smith. Efficient Management of
   Parallelism in Object Oriented Numerical Software Libraries. Modern
   Software Tools in Scientific Computing. E. Arge, A. M. Bruaset and
   H. P. Langtangen, editors. 163--202. Birkhauser Press. 1997.
