Those are Polish book covers from 70`s and 80`s. The graphics, typography and colours are fantastic. I love the swallow illustration which reminds me of Charley Harper's style.
That’s a refreshing take on book covers. Flat. Simple. Textural.
Over at the excellent blog Journey Round My Skull was posted an amazing collection of Polish book covers.
And here you can find archive of book covers design and designers from around the world.