The New Media Museum has a comprehensive collection of Microsoft operating system and productivity software for IMB/Compatibles and Macintoshs as well as Xbox consoles with games and peripherals.
These are some of the most relevant books in the collection. More…
Computer History Museum Makes Historic MS-DOS and Word for Windows Source Code Available to the Public (Computer History Museum)
Microsoft MS-DOS Early Source Code (Leonard J. Shustek, Computer History Museum)
The Software Library: MS-DOS (Internet Archive)
Microsoft Word for Windows Version 1.1A Source Code (Leonard J. Shustek, Computer History Museum)