Agard, J.  <br/><br/>
International Geological Congress : report of the eighteenth session, Great Britain, 1948. Part 7. Symposium and proceed. of sect. F. The geology, paragenesis and reserves of the ores of lead and zInc / 
J. Agard; K. C. Dunham. 
 - London :   International Geological Congress,   1950.