Currie, Ian F.; Bond, Susan G.; Morison, J. D. "ALGOL 68-R, Its Implementation and Use" pp.360-363.

Freiman, C. (1971) Freiman, C. V. et al (Ed) Information Processing 71, Proceedings of IFIP Congress 71, Ljubljana, Yugoslavia, August 23-28, 1971  

Languages mentioned ALGOL 68-R {1970}