In the UK, ISBN agency Nielsen says that new titles published during 2011 declined slightly from the previous year, totaling 149,800 books. Of those 35,000 were ebooks (or online resources), 28,000 were hardcovers, and 71,000 were paperbacks. The Nielsen UK figures have not reflected the same explosion in ISBN-carrying content as the US, where “POD farms” and self-publishers have accounted for many hundreds of thousands of units. Nor does the Nielsen data–or even Bowker’s US data–tabulate the increasing number of self-published ebooks that carry only proprietary store identifiers (like Amazon’s ASIN) rather than receiving registered ISBNs.
