@article{CammarotoChinniSturiale1998Optimization,
  author  = {Filippo Cammaroto and Antonia Chinnì and Giuseppe Sturiale},
  title   = {On an Extension of Ekeland's Principle for Vector-Valued Functions},
  journal = {Optimization},
  volume  = {43},
  number  = {1},
  pages   = {19--28},
  year    = {1998},
  doi     = {10.1080/02331939808844371}
}