https://baike.baidu.com/item/%E6%9F%B3%E6%B0%B8%E5%93%B2/8066861
https://www.hk01.com/%E9%96%8B%E7%BD%90/695918/%E9%9F%93%E5%9C%8B%E5%A5%B3%E6%AE%BA%E4%BA%BA%E9%AD%94%E6%AE%BA%E5%A4%AB%E6%A
https://zh.m.wikipedia.org/wiki/%E6%96%B0%E5%A0%82%E7%AB%99%E6%9D%80%E4%BA%BA%E4%BA%8B%E4%BB%B6
當與外國人做生意，自然緊張匯率，因為影響成本支出。
https://ezone.hk/article/1892914/%E9%A2%B1%E9%A2%A8%E5%A4%96%E9%81%8A%E6%97%85%E5%AE%A2%E6%B3%A8%E6%84%8F