I think there's some confusion over numbers of the complete glasses.  Ettinghausen and Grabar only suggest one for Minden (not sure where you got the figure of two from?); I got one at Germanisches Nationalmuseum, Nuremberg, from  but now I start looking more thoroughly I can't find it anywhere else; Erdmann says there are two at Namur and other sources corroborate that.  Annoyingly, I don't have access to Jstor so can't check the rest of the articles cited to see if they elaborate.  Also, for the fragments - where there is more than one fragment, it's not made explicit what the minimum number of glasses represented by those fragments is, as far as I can see. 10 fragments doesn't necessarily = 10 different glasses. 81.147.148.65