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Rubber, gutta-percha and balata
Clouth, Franz, (1903)
Rubber
(1956)
Seasonal trends of rubber production
(1932)
Fourth Pan American Commercial Conference, October 5th-13th, 1931 : final act (with annexes and a summary of the work of the conference)
(1931)
Commerce of Mexico (partial) : latest reports from Mexican official sources : trade by countries and ports
Rowe, L. S., (1923)
El estudio del cultivo de roza
Conklin, Harold C., (1963)