Adriaan van Wijngaarden, B. J. Mailloux, John Edward Lancelot Peck, Cornelis H. A. Koster, Michel Sintzoff, C. H. Lindsey, Lambert G. L. T. Meertens, R. G. Fisker. Revised Report on the Algorithmic Language Algol 68. Springer, 1976. [doi]
Abstract is missing.