Literacy in Traditional Societies by Jack Goody (1975):

the somewhat extravagant work by Marshall McLuhan (…) elaborates on themes developed also at Toronto by Innis (…) and later by E. A. Havelock (whose Preface to Plato appeared in 1963)… (footnote on p 1)

This is an early example of the “later by E. A. Havelock” persuasion. Goody had, of course, no interest at all in the chronology he mentions in passing here and had done no research into it. But the notion gained traction and would be repeated in many quarters. 

Later, after 1990 when Patterson published Innis correspondence from 1951 showing his appreciation of Havelock’s orality research at that time, the “later by E. A. Havelock” thesis was back-dated from 1963 to 1951. But the publication date of that research was retained. Here is Jeffrey in 1997:

[In a letter to Frank Knight from 21 May, 1951 published by Patterson] Innis writes about Havelock’s work on “the question of the shift from the oral to the written tradition in Greek culture” which [work] was not published until 1963. (Jeffrey, 208)