Hist�oria de pesquisa de petr�oleo no Brasil,

by Oliveira, Euzebio Paulo de
Published 1940

Diamante e carbonado no estado da Bahia,

by Leonardos, Othon Henry, 1899-
Published 1937

A industria extractiva do ouro,

by Moraes, Luciano Jacques de
Published 1937

Ferro no Estado da Bahia,

by Leonardos, Othon Henry, 1899-
Published 1937