"The Wonderful Adventures of Nils" is a famous work of fiction by Swedish author Selma Lagerlof, published in two parts in 1906 and 1907. The background for publication was a commission from the National Teachers Association in 1902 to write a geography reader for the public schools.
"She devoted three years to Nature study and to familiarizing herself with animal and bird life. She has sought out hitherto unpublished folklore and legends of the different provinces. These she has ingeniously woven into her story." (From translator Velma Swanston Howard's introduction.)