Xerox is the company where Smalltalk was developed. Alan Kay wrote about it in
Alan Kay's history of Smalltalk of 1992:
http://www.metaobject.com/papers/SmallHistory.pdf
This was written by Alan Kay in the early nineties. It gives a lot of
background and insight into the people and processes that produced Smalltalk and
it is well-written.
It's almost 4 MB and the only problem is that in Adobe Acrobat 5.0 I had to flip
pages and take some care with scrolling to read it through in the right order.
And it's somewhat interesting to know that Xerox at some point sold Smalltalk80 to Apple for the sum of .... $ 1, and that Apple enabled the original developers of Smalltalk to make Squeak and make it free and open source.