[2021-06-17]. (原始内容存档于2021-06-17). Crowell, T.Y. Crowell's Dictionary of Business and Finance. New York: Thomas Y. Crowell Company. 1923: 121 [2021-05-04]
LLC. 2020. ISBN 978-0-7948-4705-0. Crowell's Dictionary of Business and Finance. New York: Thomas Y. Crowell Company. 1923: 121 [2021-05-01]. OCLC 1123997620
Swiatek,第379–380頁. Bowers,第404頁. Yeoman,第1094頁. Crowell's Dictionary of Business and Finance. New York: Thomas Y. Crowell Company. 1923: 121 [2022-01-22]. OCLC 1123997620