Internet (pre-)History
When I was a wee hacker I wrote a manual for using the Internet, which had recently become available to researchers at the University of Puerto Rico. The Office of Information Systems later updated and republished the manual, and there are several copies in the UPR library system. Last week we located a copy, and the library staff digitized it.
Ortiz Zuazaga, Humberto; Muir, James A. Using UPREnet to communicate with other colleagues and researchers and to access remote information resources all around the world University of Puerto Rico, Office of Information Systems, 1991.
https://ccom.uprrp.edu/~humberto/images/UPREnet-manual.pdf
If I read the manual right, the main campus computer used for email didn't even have a TCP/IP stack, and the entire bitnet network was manually routed.
A few years ago I put together a presentation on the history of research networking at the UPR for a conference:
Research Networking in Puerto Rico. Presented at the Caribbean Telecommunications Union Caribbean Information Communication Technology Roadshow, San Juan, Puerto Rico, April 15, 2011.
research-networking.pdf