Diaconescu-Goodman-Myhill Theorem/Historical Note

Historical Note on Diaconescu-Goodman-Myhill Theorem
The proof of the Diaconescu-Goodman-Myhill Theorem was first published in $1975$ by.

It was later independently rediscovered by and  and published in $1978$.

However, the first appearance of the result itself was in 's $1967$ work, where he set it as an exercise, without including a solution.