Harvard University Press’ Belknap Press imprint has an unlikely hit on its hands. Sales of Capital in the Twenty-First Century by French economist Thomas Piketty have steadily increased each week as the author makes more media appearances to discuss his book that has been widely praised as one of the most important works in recent years on the subject of economic inequality.

Since its release on March 10, Capital has sold a total of 78,000 copies HUP reported, in a mix of 65,000 hardcover copies and 13,000 e-books.

HUP has gone back to press for six more printings to satisfy demand not only in the U.S., but overseas as well. Two of the new printings are targeted for the U.S. with two headed for HUP’s European office where demand is picking up. The press is also devoting two printings to India where the book is set to be released next month.