6. a small strip of coloured cloth signifying membership of an order or award of military decoration, prize, or other distinction. 7. a small, usually looped, strip of coloured cloth worn to signify support for a charity or cause: a red AIDS ribbon.
The books burned were Jewish, Marxist, Bolshevik, or other disreputable or non-German books. These included the works of Heinrich Heine, Sigmund Freud, Thomas Mann, Erich Maria Remarque, Albert Einstein, Walter Benjamin, Karl Marx, Jack London and Margaret Sanger.
Hardcover books are often printed on acid-free paper, and are much more durable than paperbacks, which have flexible, easily damaged paper covers. Hardcover books are marginally more costly to manufacture.