I went looking for the three IPC reports:

For more information about this system, see:
- "Interprocess Communication Extensions for the UNIX Operating System: I - Design Considerations", Rand Corporation, Report R-2064/1-AF, June 1977.
- "Interprocess Communication Extensions for the UNIX Operating System: II - Implementation", Rand Corporation, Report R-2064/2-PR, April 1977.
- "UNIX TCP User's Guide", Bolt Beranek and Newman Inc., Report No. 3724


And could only find the first one online at https://apps.dtic.mil/dtic/tr/fulltext/u2/a044200.pdf

Do we have the other two anywhere?

Warner