Reference: for a similar type Han Dynasty jade bi disc see no.77, A Catalogue of The National Palace Museum's Special Exhibition of Circular Jade, National Palace Museum, Taipei, 1995-96. As Rawson states in Chinese Jade from the Neolithic to the Qing, p.253, "Although new types of decoration for bi discs and rings were introduced in the late Eastern Zhou and Han periods, some examples with relief spirals, which may either illustrate the continuation of the Zhou tradition, or may even date from Zhou times, were used by the Han, as in the tombs at Mancheng".