304. [1] No person shall be deemed to publish a defamatory libel by reason only that he sells a book, magazine, pamphlet or other thing, other than a newspaper that contains a defamatory matter if, at the time of the sale, he does now know that it contains the defamatory matter.
[2] Where a servant, in the course of his employment, sells a book, magazine, pamphlet or other thing, other than a newspaper, the employer shall be deemed not to publish any defamatory matter contained therein unless it is proved that the employer authorized the sale knowing that