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Historical summary of gold, silver, copper, lead, and zinc produced in California 1848 to 1926
Hill, James Madison, (1929)
Analysis of Selected Seasonality Effects in the Following Metal Markets : Gold, Silver, Platinum, Palladium and Copper
Borowski, Krzysztof, (2015)
What Is Wrong with Gold, Silver, Uranium, Platinum, Aluminum and Copper?
Arsov, Doc. Dr. Aleksandar, (2014)
The Central Bank of Canton
Kann, Eduard, (1929)
Copper banknotes in China
The mystery of the Hongkong Dollar
Kann, Eduard, (1930)