OO was already invented and Simula 67 is even referenced in the paper, but not yet recognized or understood in its significance; the claim about Algol 60 ("an improvement .. on nearly all its successors") is pretty bold.
And in what respect does this contradict my statement? The paper appeared in 1973.
(By the way: Simula 67 was mostly influenced by Simula I; both Simula versions are an extension of Algol 60; with some minor exceptions Algol 60 is a subset of Simula 67 - as later Stroustrup did it with C and C++).
