Underwood, Oscar Wilder (1913). Tariff schedules: Hearings before the Committee on ways and means. Strings for Musical Instruments. U.S. Government Printing Office. стр. 5691. Приступљено 27. 2. 2010. „[T]here is no such thing as crude catgut or catgut unmanufactured. Catgut is a manufactured article and a finished product; the crude form are the intestines or guts of sheep or other animals.”CS1 одржавање: Формат датума (веза)