APA (7th ed.) Citation

Horn, C. L. (1956). The iron ore industry of Minnesota and the problem of depleted reserves. [publisher not identified].

Chicago Style (17th ed.) Citation

Horn, Charles L. The Iron Ore Industry of Minnesota and the Problem of Depleted Reserves. Princeton? N. J.: [publisher not identified], 1956.

MLA (9th ed.) Citation

Horn, Charles L. The Iron Ore Industry of Minnesota and the Problem of Depleted Reserves. [publisher not identified], 1956.