Barbey, S; M. Kempe, and A. Strohmeier. «Object-Oriented Programming with Ada 9X». Draft Technical Report. Swiss Federal Institute of Technology in Lausanne Software Engineering Laboratory, 1993 [Consulta: 15 desembre 2013]. «Ada 83 itself is generally not considered to be object-oriented; rather, according to the terminology of Wegner [Weg 87], it is said to be object-based, since it provides only a restricted form of inheritance and it lacks polymorphism.»