Possible Clues:

• 13th-century literary classic
• Studied Dante's collected verse works
• Epic poem that begins with the "Gylfaginning"
• Collection of old poems mostly summed up
• Old Norse literature
• Primary source for Scandinavian mythology
• Ancient Icelandic writings
• Work that includes the Skáldskaparmál
• Books of past and unremembered days
• Was summing up abridged old poetry collection