(ref.doc)toplas22-3

ACM Transactions on Programming Languages and Systems
May 2000

p 506 Integrating Object-Oriented Programming and Protected Objects in Ada 95
by A. J. Wellings, B. Johnson, B. Sanden, J. Kienzle, T. Wolf and S. Michell
  An inheritance anomaly [Matsuoka and Yonezawa 1993] exists if the
  synchronization between operations of a class is not local but may
  depend on the whole set of operations present for the class.