Wittmaack, M. F. (1999). Existence of multiple ordered solutions for a similinear elliptic boundary value problem. Universidad de La Serena.
Citazione stile Chigago Style (17a edizione)Wittmaack, Melitta Fiebig. Existence of Multiple Ordered Solutions for a Similinear Elliptic Boundary Value Problem. La Serena: Universidad de La Serena, 1999.
Citatione MLA (9a ed.)Wittmaack, Melitta Fiebig. Existence of Multiple Ordered Solutions for a Similinear Elliptic Boundary Value Problem. Universidad de La Serena, 1999.
Attenzione: Queste citazioni potrebbero non essere precise al 100%.