Six similar specimens are in the Royal Ontario Museum in Toronto (Hayes, nos. 271, 272, 291, 294, 323, and 474). See also Goldman, no. 25, Isings (1971), no. 241 (at Heerlen), Whitehouse (1997), nos. 286 and 289, and Whitehouse (1998), no. 94. - Ancient Glass in the University of Colorado Museum