Memoirs of the Archæological Survey of India. A Hoard of Silver Punch-Marked Coins from Purnea

The most important and interesting part of the study of these coins is the attempt to classify the coins according to the various symbol-groups and to gather therefrom the significance of the individual punches and the various combinations. [...] Walsh/ says The reason for this large amount of copper is due to the fact that apart from any proportion of alloy in the coin several of the coins have been debased by the addition of molten copper to the original silver coin presumably to make up for the weight. [...] The five symbols that are found on the obverse side are bigger in size than most of the symbols occurring on the coins of the Classes II and III. [...] The imperfect impression of the symbols stood in the way of drawing them correctly and including them in the chart of symbols. [...] c and d have not got any of the symbols 30 43 '57 or 88 and have not the same reverse stamp of the vars.