nostr:npub19d9p04u4xfysdy92fycw947jrca3xve2gnsauysshzewxvmz8dms6kf02p 
Hopfield 1982 and his accompanying historical paper that explains the context: "Now what?". That doesn't exist anymore on his webpage (I've reached out to get that fixed; will email it to you).

https://www.pnas.org/doi/10.1073/pnas.79.8.2554