The Four DS2406 project is essentially the same one that uses a pair of them twice. The system has one DS2406 attached to one gate. These gates are part of the SN7437.

That particular part has its outputs attached to four of the inputs on the SN7472. There are four inputs per J and K input for this F/F. Two are used for each of the gates. Essentially all four switches need to be turned on for the F/F to toggle.