For another bottle of this type, see The Radiance of Jade and Clarity of Water: Korean Ceramics from the Ataka Collection, exh. cat. (Chicago: The Art Institute; New York: Hudson Hills Press, 1992), pl. 73. The catalogue entry remarks that scholars have not determined the exact procedure the Joseon potter followed for square porcelain bottles. One theory holds that he used four individual molds to form each side, pressed them together and then added the top and base. Another holds that the potter molded the clay into a dense cube that he hollowed out.