Everything upstairs is good, but if we want to say the greatest knight literature in the Middle Ages and the peak of bard's poetry, it must be Song of Roland. It is no exaggeration to say that it has both Homer's broad and elegant beauty and Dante's bold and powerful brushwork. This is really a great epic.
Speaking of Nordic myths, you can buy Eda from Yilin Publishing House, where all Nordic fairy tales come from. In addition, the Nordic Myth ABC written by Fang Bi (pen name Mao Dun) is also worth reading. Personally, I think it is the best book to sort out Nordic myths now.