https://archive.org/details/bstj27-4-623 : "A Mathematical Theory of Communication", Shannon, C. E.
https://archive.org/details/bstj57-6-1991 : "UNIX Time-Sharing System: The C Programming Language.", Ritchie, D.M.; Johnson, S.C.; Lesk, M.E.; Kernighan, B.W.
https://archive.org/details/bstj39-6-1381 : "Signaling Systems for Control of Telephone Switching.", Breen, C.; Dahlbom, C.A. (The famous/infamous issue which leaked the 2600 Hz tone to the world, forming the foundation of blue boxing and phreaking as a whole.)
More about the history of blue boxing: https://spectrum.ieee.org/tech-history/cyberspace/phreaking-...
The Esquire article, Secrets of the Little Blue Box by Ron Rosenbaum, (October 1971) which introduced the theory and phreaking to the world: http://www.lospadres.info/thorg/lbb.html
All this work was first published in the Bell System Technical Journal.
Much better sidelobe rejection and front/back ratio performance than traditional parabolics. What's old is new again.
I know you're talking about the Holmdel Horn (steerable) used for earlier transatlantic satellite relay experiments. But there are still a great many sites across the USA with 6 GHz horns in place on towers, mostly doing nothing.
I have seen tower crews with cutting torches cutting up KS-15676 horn antennas because they're too big and bulky to economically get off a tower any other way.
Wonder if a some point it may be possible to synthesize a compact, ultra wide-band, minimal side loops ultrahorn for HF. Focused 24dBd signals on 20 meters without the need for a yagi antenna farm would be nice.
Surprisingly there are not the best choices and prices/competition for serious ISP connectivity in the building, for dedicated 1/10GbE business class IP transit with carriers that I would consider in the "top ten" list for transit providers. At least not compared to some places in/near Seattle, somewhere close to Infomart Dallas, or the suburban sprawl around Ashburn, VA.