Mgbasa ozi ọla kọpa
akara 1870, enweela ọtụtụ mbọ iji ike ihie iko, n'ụdị a, ọnụ ya.
Nke a bụ ndepụta nke cartel ọla kọpa na awụ nke 20:
- Njikọ Mbupụ ọla kọpa, CEA, 1918–1923
- Ndị na-ebupụ ọla kọpa, Inc., CEI, 1926–1932
- International Copper Cartel, ICC, 1935 – 1939 (nke World Copper Agreement mebere)
- Kansụl gọọmentị etiti nke mba ndị na-ebupụ ọla kọpa, CIPEC, 1967–1988
Ọgụgụ ọzọ[dezie | dezie ebe o si]
- Herfindahl, O. (1959) Ọnụ ego ọla kọpa na ọnụ ahịa: 1870-1957, RFF, Baltimore.