The Balkan Mountain Range
A product is commodity when it is fungible. Commodities are raw materials like corn, wheat, copper, crude oil, etc.
A primary source comes from someone who lived during the time of the event or they were at the event. The reason why historians want primary source is because it is more likely to be factual and will give the best information. For example, at the signing of the declaration of independence several of the men who signed it wrote diaries . That would be considered a primary source, because those men were there and saw it as well as documented the event.
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