^Pamela Spence Richards, Wayne A. Wiegand, Marija Dalbello. A History of Modern Librarianship: Constructing the Heritage of Western Cultures: Constructing the Heritage of Western Cultures. ABC-CLIO. 2015: 14 [2018-06-08]. ISBN 978-1-4408-3473-8. (原始内容于2020-10-04).
^Statsbiblioteket. Aarhus City Archives. [2016-02-18]. (原始内容存档于2016-02-19) (丹麦语).