For those of you who are interested in the world of eBooks and self-publishing, I have a bit of a Barnes & Noble eBook sales mystery that I’m trying to unravel.

Some background: like many authors these days, Amazon.com has always sold the most copies of my eBooks.

If Amazon sells 100 copies of The Painted Darkness in a month, Barnes and Noble will sell 50, Apple will sell 15, and Sony will sell 8.

That trend has been pretty steady. For the sake of discussion, let’s say Barnes and Noble might have had sales like this for The Painted Darkness to start the year:

January: 52
February: 51
March: 55
April: 59

Everything was pretty much normal, in other words. But suddenly, there was a surge:

May: 177
June: 220
July: 447

And I have absolutely no idea why. I’ve done no additional advertising. There have been no new major reviews of note. I’ve had no new releases to bring attention to my work in general.

The only thing that has changed is that the trade paperback edition, priced at $9.99, came out this spring, but I don’t see how the two events could be connected.

Anyone have any thoughts?