Why Is Hitler’s Mein Kampf Topping eBook Charts? (TIME, 1/7/2014)
Still not sure if it adds up. The number of different editions available–Amazon sells 6 ebook versions of Mein Kampf alone–coupled with the increased popularity of ebooks has also boosted sales.
Actually, I stopped after finding 7 versions.
According to Theresa Ragan's "Sales Ranking Chart", an Amazon sales ranking of 50,000 to 100,000 translates into about 1 sale per day. 1. O-n-e.
And here's what I found at CNET. It's from March 19, 2009.