The University of Wisconsin-Milwaukee has finished processing a large collection of Pabst Brewing Company records and those are now available for use by researchers.
The university received the collection in 2000, just as I started working on my book, but the papers were not processed until 2006. Translation: I was not able to use them (which was, sigh, the story of my life when I was working on the book.)
The vast majority of the records are financial in nature (ledger books, stock records, receipts), but there's also a large scrapbook related to Captain Pabst and the company itself. There are also some "private ledgers," and as I learned from the few scattered ones I found at other libraries, those can yield a great deal of information! You can see the finding aid here.