New York Times:

In a sharp answer to Amazon and its expanding publishing efforts, Barnes & Noble said on Tuesday that it would not sell books released by Amazon Publishing in its bookstores.The ban includes books released by New Harvest, a new imprint of Houghton Mifflin Harcourt that recently struck a deal to publish and distribute books released by Amazon Publishing’s unit based in New York.It also seemed unlikely that many of the 1,900 independent bookstores in the United States would be willing to stock Amazon books.

To be clear, the B&N ban only applies to books from the publishing arm of Amazon – not all books sold through Amazon.com.