"Great works of literature have frequently been produced by authors writing under assumed names. Despite readers' curiosity and the public's interest in identifying the creator of a work of art, an author generally is free to decide whether or not to disclose her true identity. The decision in favor of anonymity may be motivated by fear of economic or official retaliation, by concern about social ostracism, or merely by a desire to preserve as much of one's privacy as possible. Whatever the motivation may be, at least in the field of literary endeavor, the interest in having anonymous works enter the marketplace of ideas unquestionably outweighs any public interest in requiring disclosure as a condition of entry."