There's also Backus' "Programming in America in the 1950s – Some Personal Impressions" talk https://www.youtube.com/watch?v=EylBknGtkqA at the 1976 First International Research Conference on the History of Computing. The conference paper is pp. 125-135 https://archive.org/details/historyofcomputi0000inte/page/12... in A History of Computing in the Twentieth Century (1980, Metropolis, Howlett and Rota eds., ISBN 0-12-491650-3 ). Naturally it also got a session at the first History of Programming Languages conference in 1978 https://dl.acm.org/doi/10.1145/960118.808379 at which Backus spoke again https://dl.acm.org/doi/book/10.1145/800025#sec2 . And of course it's one of the stars of Jean Sammet's 1969 Programming languages: history and fundamentals book (ISBN 0137299885) where the FORTRAN section begins on p. 143 https://archive.org/details/programminglangu00unse/page/143/... .