Bell System Technical Journal had huge influence on the phreaking community. It could be said that without it there would have been no phreaking community. Some of the most influencial was issue number 6 from 1960 called Signaling Systems for Control of Telephone Switching. It detailed the MF tones that phreaks would later use to make free long distance calls. Bell Systems also published Bell Laboratories Record which was less technical and easier to read since it was meant for the general public. A more obscure book by Bell Systems was Notes on Distance Dialing, that was meant for engineers of independent telephone companies.