Here is the author note from my picture book.—Aaron
The Norwegian tale “Master Maid” is found in the collection of the great 19th‑century folklorists Peter Asbjörnsen and Jörgen Moe. Classified in the Aarne-Thompson index as “The Girl as Helper in the Hero’s Flight” (tale type #313), this is one of the finest versions of a tale known on every continent, and even told in ancient Greece as the myth of Jason and Medea.
The original story is much longer than this retelling and relates further adventures of Leif and Master Maid after their escape from the troll. You’ll find it in many collections, including Folktales of Norway, edited by Reidar Christiansen, University of Chicago Press, 1964, and East o’ the Sun & West o’ the Moon, translated by George Webbe Dasent, Dover, New York, 1970.
Maid is short here for maiden, and Master Maid is a Norwegian way of saying “Supergirl.”