Grahne91'

@book{DBLP:books/sp/Grahne91,
  author    = {G{\"o}sta Grahne},
  title     = {The Problem of Incomplete Information in Relational Databases},
  publisher = {Springer},
  series    = {Lecture Notes in Computer Science},
  volume    = {554},
  year      = {1991},
  isbn      = {3-540-54919-6},
  ee        = {http://dx.doi.org/10.1007/3-540-54919-6},
  bibsource = {DBLP, http://dblp.uni-trier.de}
}