[Villiers88] D. Villiers and S. Solms, Using NLC-Grammars to Formalize the Take/Grant and Send/Recieve Security Models, Quaestiones Informaticae, V6(1) pp 54-62, Many, 1988. [This paper introduces a formalism for describing and analyzing take/grant and send/recieve security models. This language is now commonly used for analysis and specification in distributed key management systems.]