The paper by Melinda Varian sounds interesting.
Here is the quote from her very interesting paper ( I strongly recommend to read at least the beginning of this 73 pages paper -- it provides new insights into how two most interesting operating system Unix and VM/CMS were influenced by Corbato's CTTS and MIT Multix project)
As of 2021-03, the link http://pucc.princeton.edu/~melinda/
is stale, but I found the paper (167 pages)
VM AND THE VM COMMUNITY: Past, Present, and Future by Melinda Varian, April, 1991