The term "book token" generally refers to gift vouchers for purchasing books, but it also describes several literary works including Sharon Bolton’s thriller about a dangerous inheritance, a romance novel by Beverley Kendall, and a 19th-century American literary annual [24, 16, 11, 3, 18, 9]. The concept also covers modern National Book Tokens, which are used to promote reading and literacy in the UK [19, 34, 35].