@incollection{CammarotoChinniDiBella2005VAA,
  author    = {Filippo Cammaroto and Antonia Chinnì and Beatrice Di Bella},
  title     = {Infinitely Many Solutions for the Dirichlet Problem via a Variational Principle of Ricceri},
  booktitle = {Variational Analysis and Applications},
  series    = {Nonconvex Optimization and Its Applications},
  volume    = {79},
  publisher = {Springer},
  pages     = {215--229},
  year      = {2005},
  doi       = {10.1007/0-387-24276-7_16}
}