In the 1950s, book clubs were very popular. Many of their books were bound in half-leather bindings – the fine material was meant to bring elegance to living-room shelves. Paperbacks that first appeared in 1951 were attractive with their linen backs.Werner Keller’s book “The Bible as History” was the best-selling non-fiction book of the 1950s. Heinrich Mann’s novel “Professor Unrat” was published in paperback under the book’s film title: “The Blue Angel.”