^Weights and Measures Act 1985. 2011-08-30 [2011-09-22]. Part II Weighing and Measuring for Trade ... 8 Units of measurement, weights and measures lawful for use for trade ... (2) No person shall use for trade—(a) the ounce troy, except for the purposes of transactions in, or in articles made from, gold, silver or other precious metals, including transactions in gold or silver thread, lace or fringe...
^Precious Metal Buyers, Gold Refiners, Gold Assayers, Waste Management. Precious metals calculator. Maguire & Strickland Refining. 2011-09-22 [2011-09-22]. This section is for those in the trade. Those in the trade include jewelers, dentists and dental laboratories who have a store front, State ID numbers and Federal ID numbers ... We do not list a dental estimating factor as there is no standard gold percentage for dental solids
^Penny(subscription required). Oxford English Dictionary 2nd. [2010-05-30]. Applied to nails, such adjectives denote the original price (in 15th c.) per hundred; as fivepenny nail, a nail which cost 5d. a hundred, tenpenny nail, a nail costing 10d. a hundred. (These names persisted after the prices fell, as they began to do in some places before 1500, and they were eventually used to designate sizes of nails.)[永久失效連結]
^H. Littlehales. Medieval Rec. London City Church. 1905Cited in the Oxford English Dictionary under "Penny" with a quote from 1426-1427.
^Coin Specifications(table). About us. 美国铸币局. September 22 [September 22, 2011]. （原始内容存档于2009-11-11）. The following table gives specifications for The United States Mint legal tender coins presently in circulation请检查|date=中的日期值 (帮助)