For a country whose government didn’t recognize the people’s right to free speech, Poland certainly had a great tradition of beautiful book covers in the 20th century. I recently found a collection of Polish book covers from last century that are so much more simple and beautiful than most contemporary designs.
Many of them use a collage style, inspired by the Bauhaus in the 1930s by Herbert Bayer and László Moholy-Nagy (the founder of the Institute of Design in Chicago), while others are more inspired by the Polish poster style. If you look at movie posters done by Saul Bass from California, the torn paper collage style was dominant in the US during the same time.
There appears to be some level of freedom in these book covers as the Soviet Realism style that was dominant in the USSR did not encompass Poland. Poles were largely free to move ahead with their own design language, while Russians had to adhere to a state-directed vernacular.
Visit A Journey Round My Skull blog to see a great many more covers.