@techreport{GuttmannMoeller2006,
  author    = {Walter Guttmann and Bernhard M{\"o}ller},
  title     = {Modal design algebra},
  institution = {Fakult{\"a}t f{\"u}r Angewandte Informatik},
  series    = {Reports / Technische Berichte der Fakult{\"a}t f{\"u}r Angewandte Informatik der Universit{\"a}t Augsburg},
  number    = {2005-15},
  year      = {2006},
}