From Guns.com:

The U.S. 9th Circuit on Tuesday upheld an Alameda County law barring gun stores within 500 feet of residential properties in a blow to gun rights advocates.

The court held that local governments could regulate the sale of firearms so long as would-be buyers were still able to purchase them somewhere in the area and that the Second Amendment does not protect the ability to engage in gun sales.

The obvious question now is: Do you have a constitutional right to sell books?