With the publication of "I Know Why the Caged Bird Sings", she publicly discussed aspects of her personal life. She was respected as a spokesperson for black people and women, and her works have been considered a defense of black culture. Her works are widely used in schools and universities worldwide though attempts have been made to ban her books from some U.S. libraries. Angelou's most celebrated works have been labeled as autobiographical fiction, but many critics consider them to be autobiographies. She made a deliberate attempt to challenge the common structure of the autobiography by critiquing, changing and expanding the genre. Her books center on themes such as racism, identity, family and travel.