BibTeX
@BOOK{
         Langtangen1999CPD,
       author = "Hans Petter Langtangen",
       title = "Computational Partial Differential Equations: {N}umerical Methods and {D}iffpack
         Programming",
       series = "Lecture Notes in Computational Science and Engineering",
       publisher = "Springer",
       address = "Berlin",
       key = "Langtangen1999CPD",
       referred = "[Tijskens2001EOO].",
       year = "1999",
       number = "2",
       isbn = "3540652744"
}