@article{Geo:83b,
  journal = {Studia Logica},
  volume = {42},
  title = {Chang's modal operators in algebraic logic},
  year = {1983},
  fjournal = {Polish Academy of Sciences. Institute of Philosophy and Sociology.
              Studia Logica. An International Journal for Symbolic Logic},
  pages = {43--48},
  number = {1},
  author = {Georgescu, George},
}