Nussbaum, Arthur (1957). A History of the Dollar. New York: Columbia University Press. p. 56. https://archive.org/details/historyofdollar0000nuss. "The foreign coins remained in circulation [in the United States], and the more important among them, especially the Spanish (including the Mexican) dollars, were declared by Congress on February 9, 1793, to be legal tender. The dollar sign, $, is connected with the peso, contrary to popular belief, which considers it to be an abbreviation of 'U.S.' The two parallel lines represented one of the many abbreviations of 'P,' and the 'S' indicated the plural. The abbreviation '$.' was also used for the peso, and is still used in Argentina."
Aiton, Arthur S.; Wheeler, Benjamin W. (May 1931). “The First American Mint”. The Hispanic American Historical Review11 (2): 198. doi:10.1215/00182168-11.2.198. JSTOR2506275.
jstor.org
Aiton, Arthur S.; Wheeler, Benjamin W. (May 1931). “The First American Mint”. The Hispanic American Historical Review11 (2): 198. doi:10.1215/00182168-11.2.198. JSTOR2506275.