1. Anonym: J. Rubber Res. Inst. Malaya 9 (1939).
2. Planters’ Bull. Rubber Res. Inst. Malaya, Nr. 23, 35 (1956).
3. Manuring program for young replantings. Planters’ Bull. Rubber Res. Inst. Malaya, Nr. 35, 46–48 (1958).
4. Correction of manganese deficiency. Planters’ Bull. 53, 63–66 (1961).
5. Bolle-Jones, E. W.: Physiol. Plant. (Copenhagen) 8, 606–629 (1955).