^ 1.01.1郑宝鸿. 圖片香港貨幣. 三联书店(香港)有限公司. 1 August 2012: 40. ISBN 978-962-04-3278-1(中文(香港)). 外国银元(即贸易银)于明朝时已开始流入中国。...由于中国人不喜欢洋货,外国人不能用以物易物的方式交,只能用银元来购买中国的丝、茶叶和瓷器等等。 当时的外国银元有葡萄牙的十字银元、日耳曼帝国的塔勒、荷兰的马剑幤、美国的五先令、美国的银元以及西班牙的“本洋”等。
^ 2.02.12.2Larry Allen. The Encyclopedia of Money. ABC-CLIO. 2009: 70. ISBN 978-1-59884-251-7(英语). In 1895, the United Kingdom, itself on the gold standard, began issuing silver dollars, called "trade dollars," specifically for trade with the Far East. British trade dollars bore inscriptions in English, Chinese, and Malay-Arabic. Briefly during the latter 19th century, the United States issued a special trade dollar designed specifically to compete with the Mexican dollar in Far Eastern trade. The Chinese called these various silver dollars yuan, meaning "round things," and yuan became the standard monetary unit in China and modern Taiwan.