For a discussion of jade zhang see Yang Boda, "Jade Zhang in the Collection of the Palace Museum, Beijing", Orientations, Selected Articles from 1983-2003, pp. 141-8, where a very similar example, attributed to the Shimao culture, c. 2000-1500 BC, in the Palace Museum, Beijing, is illustrated, p. 145, fig. 8. Another similar jade zhang, but with incised linear designs at the base of the blade, excavated from the Shimao site, Shenmu, Shaanxi province, is illustrated in The Complete Collection of Jades Unearthed in China - 14 - Shaanxi, Beijing, 2005, p. 19. Other similar jade zhang include two in the British Museum illustrated by J. Rawson, Chinese Jade from the Neolithic to the Qing, British Museum, London, 1995, p. 189, fig. 3, which are dated Neolithic period, northwest China, c. 2000-1000 BC, and the several examples in the Winthrop Collection illustrated by M. Loehr in Ancient Chinese Jades, Fogg Art Museum, Harvard University, Cambridge, 1975, p. 170, nos. 219-20, and pp. 172-75, nos. 223-27.