Maxwell-Lefroy, E. <br/><br/>
Bulletin of the Institution of Mining and Metallurgy,  ;   No. 135 

 - Londres-XXK :   The Institution of Mining and Metallurgy,   1915. 
 - p. 1-18 :   map. 
 - Irregular 
 - No. 135(Dec.1915) 
 - Bulletin of the Institution of Mining and Metallurgy,  ;   No. 135 .
 - Reino Unido.   The Institution of Mining and Metallurgy,. .