This is from the Edsger W. Dijkstra Archive. This entry is 667, included in the numerical index here that covers the years 1976 to 1979: https://www.cs.utexas.

This is from the Edsger W. Dijkstra Archive. This entry is 667, included in the numerical index here that covers the years 1976 to 1979: https://www.cs.utexas.edu/~EWD/index06xx.html https://www.cs.utexas.edu/~EWD/index06xx.html The entries ascend in date as they ascend in number. I believe that the date for this is 1978 since it sits between entry 665 "Trip report E.W.Dijkstra, U.K. – Bahamas – U.S.A., 11–30 April 1978" and entry 674 "Trip report E.W.Dijkstra, Zürich, 2–7 July 1978."