@book{ BA03032947,
  author    = "Berger, Melvyn Stuart",
  title     = "Nonlinearity and functional analysis : lectures on nonlinear problems in mathematical analysis",
  publisher = "Academic Press",
  year      = "1977",
  series    = "Pure and applied mathematics",
  number    = "74",
  URL       = "https://ci.nii.ac.jp/ncid/BA03032947"
}