I fully agree with this recommendation of Fred Hanna's book. I downloaded the Kindle version from Amazon.com, and read it on my iPad via the Kindle app. Great collection of essays.
I am also currently reading "in Search of Pipe Dreams". I also recently read a book called " The Pipe Smokers Tobacco Guide", not sure on the author. And is very technical, but still a good short read. I got it from smokingPipes.com.
I remember reading Pipesmoking: A 21st Century Guide by Richard Carleton Hacker years ago. I would read it again but it's not on Kindle. I remember at the time I liked it.