Jan Kroon, Rudolf Jan Heijink, Ed Brinksma (Eds.): Protocol Test Systems, IV, Proceedings of the IFIP TC6/WG6.1 Fourth International Workshop on Protocol Test Systems, Leidschendam, The Netherlands, 15-17 October, 1991.IFIP Transactions C-3, North-Holland 1992, ISBN 0-444-89517-5