@book{Smullyan1968,
  title     = {{F}irst-{O}rder {L}ogic},
  language  = {eng},
  publisher = {Springer-Verlag},
  year      = {1968},
  isbn      = {9783642867187, 3540040994},
  author    = {Smullyan, Raymond M.}
}

@article{Henkin96,
  author  = {Leon Henkin},
  title   = {The Discovery of my Completeness Proofs},
  journal = {Bulletin of Symbolic Logic},
  volume  = {2},
  number  = {2},
  pages   = {127--158},
  year    = {1996}
}
