[TUHS] looking for source code to University of Illinois "Network Unix"

[Paul Ruizendaal]

Hi,

I'm looking for the source code to "Network Unix" as described here:
https://tools.ietf.org/html/rfc681
and/or its later development described here:
https://archive.org/details/networkunixsyste243kell

Actually, I'd be happy with finding the source code to any version of this Network Unix. This version of Unix had fairly wide use in the Arpanet community and was in use at several universities and organizations (e.g.: Rand, BBN, etc.)

Would anybody here know of a surviving copy?

Many thanks in advance,

Paul