<sod>* <span id="Weller"></span>Weller G 1976, ''Cleaning and Preservation of Coins and Medals,'' S J Durst, New York, ISBN 0915262037<eod>
<sod>* <span id="Weller"></span>Weller G 1976, ''Cleaning and Preservation of Coins and Medals,'' S J Durst, New York, ISBN 0-915262-03-7<eod>