Of course, I have to list my books:
The earlier versions of my SQL Server Internals book, back when it used to be called Inside SQL Server, contained a chapter on the History of SQL Server. I had to remove that chapter due to space limitations in later versions, but you can download a PDF of the chapter as it appeared in Inside SQL Server 2000.
In addition to my In-Memory OLTP Internals book, Red Gate has dozens of other short, focused very technical books available, and most offer free downloads of the PDF version.
And there are other great SQL Server reads as well. Please take a look at this one from my former technical editor:
Dozens of great bloggers including lots of SQL Server MVPs at SQLBlog!
Check out the blog posts by members of the SQL Team at Microsoft. Lots of great stuff, include lots of in-memory OLTP information!