Answer
The answer is 1913-1931. The Swedish Academy is an academy that awards the Nobel Prize in Literature. Karlfeldt was a poet and a member of the Swedish Academy. He was also the secretary of the Swedish Academy from 1913 to 1931. During his time as secretary, he oversaw the award of the Nobel Prize in Literature to such writers as Selma Lagerlöf, Verner von Heidenstam, and Pär Lagerkvist.