By comparison, the 18 next bestselling books combined sold just 8,000 more copies during the same time period, according to the website Publishing Perspectives, which tracks book sales. (goodereader.com)
I'm now interested to see if this is usual pattern in my read as I go into my second year of tracking my books on a spreadsheet. (rathertoofondofbooks.com)
I like this service, because you can also track your book's sales history over time, even down to a particular date. (authormedia.com)