http://papers.ssrn.com/sol3/papers.cfm?abstract_id=1634126

From the abstract:

"Originally advanced by publishing industry lobbying groups, the
prevailing account of mass book-digitization projects is that
they will devastate authors and publishers, just as Napster and
its heirs have supposedly devastated musicians and music labels.
Using the impact of GBS on the revenues and operating incomes of
U.S. publishers believing themselves to be the most-affected by
it, this Article finds no evidence of a negative impact upon
them. To the contrary, it provides some evidence of a positive
impact, and proposes further empirical research to identify the
mechanisms of digitization's economic impact."