During the hey-day, PARC (Xerox not ParcPlace) published a bunch
of interesting papers called "blue & whites" (the cover's colors).

Two interesting ones are:
"An Experimental Description-Based Programming Environment: Four Reports"
"A Layered Approach to Software Design"

both by Daniel Bobrow & Ira Goldsmith.

They are good reading for anyone who wants to move away from
C-Code RCS-style version control (without having to chew off your leg :-)

Xerox is in the (slow) process of placing these papers on the Web
(I can hardly wait) but if you ask nicely they will send you copies
for free!

-- Mike Klein