Shipman81'

@article{DBLP:journals/tods/Shipman81,
  author    = {David W. Shipman},
  title     = {The Functional Data Model and the Data Language DAPLEX},
  journal   = {ACM Trans. Database Syst.},
  volume    = {6},
  number    = {1},
  year      = {1981},
  pages     = {140-173},
  ee        = {http://doi.acm.org/10.1145/319540.319561},
  bibsource = {DBLP, http://dblp.uni-trier.de}
}