Andy J. Wellings Bob Johnson Bo Sanden Jörg Kienzle Thomas Wolf Stephen Michell Integrating object-oriented programming and protected objects in Ada 95. 506-539 2000 22 ACM Trans. Program. Lang. Syst. 3 http://doi.acm.org/10.1145/353926.353938 db/journals/toplas/toplas22.html#WellingsJSKWM00