Issue No.07 - July (1970 vol.19)
The Gray code counter is stated to be an accidental result of the logical design of a binary counter which has two memory elements per stage.
Binary counter, Gray code, pulse counter, relay counter.
"Comment on "Gray Code Counter"", IEEE Transactions on Computers, vol.19, no. 7, pp. 653-654, July 1970, doi:10.1109/T-C.1970.223000