The document that is published is connected with the advices that the Copper Mining Company makes to its northamerican workers that come to work to Potrerillos Mine. It is dated in 1918 and takes part from the Archives of such Company that is kept in The Montana Historical Society Archives.  The document that is published is connected with the advices that the Copper Mining Company makes to its northamerican workers that come to work to Potrerillos Mine. It is dated in 1918 and takes part from the Archives of such Company that is kept in The Montana Historical Society Archives.