Tony Clayton: Guinea. Coins of England and Great Britain. [dostęp 2018-05-05]. Cytat: the term guinea originally referred to the place in Africa from which much of the metal was obtained (ang.).
Tony Clayton: The Change to Decimal Coinage. Coins of England and Great Britain. [dostęp 2018-05-05]. Cytat: The term guinea was (and is) used for 21 shillings (£1.05), especially in horse racing and by auction houses, although no coin of that value has been issued since 1813. (ang.).
