I can recommend Fundamental Concepts in Programming Languages by Strachey 1967. This is an eye opener and a portal into the thoughts of that time. Some ideas are as relevant today as they were back then, for instance L-value versus R-value.
There used to be a thing called the Systems and Procedures Association, was a thing in the 60s as commercial use of computers really took off. Not sure if they are still around.
If you search using Google for Strachey you get 15 hits for Lytton Strachey before you get to Christopher Strachey. That's a shame because I'm sure that Christopher Strachey has had a more lasting impact on the world.