It was pointed out to me that yesterday's post "A Fictional Book" should have been about a book that doesn't exist, is only real in a fictional world... I wonder if I missed the point, or perhaps the person who passed the template on to me is not very proficient in English... Or maybe the creator of the template didn't see the difference between a fictional book and a work of fiction.
Who knows?
I'd go for Oolon Colluphid's "Where God Went Wrong"

Today is a "Non-Fictional Book".

I will be hypocritical and assume, for the purposes of this post that they are asking me to talk about a work of non-fiction.
I've enjoyed a few non-fiction or, in the case of autobiographies, semi-fiction books.

I'll just mention two because I've been sat here for ten minutes trying to think of the titles of any others, and failing. Miserably.

Chickenhawk by Robert Mason.
Longitude by Dava Sobel.