Douglas, A. S. "Opal - A data-processing system for the 7090"

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 Autostat {1960} Statistical Programming Language OPAL {1960} CEIR data processing language