@article{johnsen15jlamp,
  author =	 "Johan Dovland and Einar Broch Johnsen and Olaf Owe and
                  Ingrid Chieh Yu",
  title =	 "A proof system for adaptable class hierarchies",
  journal =	 "Journal of Logical and Algebraic Methods in Programming",
  volume =       "84",
  number =       "1",
  pages =        "37--53",
  year =         "2015",
  doi =		 "10.1016/j.jlamp.2014.09.001",
}