Redaktionen, .-. (1901) “W. F. Willoughby: State Activities in Relation to Labor in the United States. Baltimore, The Johns Hopkins Press. April -May 1901”., Nationaløkonomisk Tidsskrift, 3. Tilgængelig hos: https://tidsskrift.dk/nationaloekonomisktidsskrift/article/view/58188 (Set: 6 december 2025).