@ARTICLE{PanseRitter2011,
  author  = {Fabian Panse and Norbert Ritter},
  title   = {Relational Data Completeness in the Presence of Maybe-Tuples},
  journal = {Ingénierie des Systèmes d'Information},
  year    = {2011},
  volume  = {15},
  number  = {6},
  pages   = {85-104}
}