[1]Arkiveret 22. oktober 2023 hos Wayback MachineR. L. Deininger: Human Factors Engineering Studies of the Design and Use of Pushbutton Telephone Sets i The Bell System Technical Journal
[1]Arkiveret 22. oktober 2023 hos Wayback MachineR. L. Deininger: Human Factors Engineering Studies of the Design and Use of Pushbutton Telephone Sets i The Bell System Technical Journal