Nygaard, K. "SIMULA - an extension of ALGOL to the description of discrete-event networks" pp520-522

Popplewell, Cicely M. (1962) Popplewell, Cicely M. (Ed.) Information Processing 62, Proceedings of the 2nd IFIP Congress, Munich, Aug. 1962. North Holland Publ. Co., 1963.  

Languages mentioned SIMULA {1962} SIMUlation LAnguage