1. The Rubber Tree Book;Maclaren de Bois,1913
2. Present possibilities of Hevea culture;Baptiste;Rev. Gen Caoutch.,1962
3. The effect of rubber price and yield per acre on estate production costs;Westgarth;J. Rubb. Res. Inst. Malaya,1964
4. Ridley, H.R. 1890–91. Annual report straits settlement. Royal Botanic Gardens for 1890 and 1891.
5. Wycherley, P.R. 1964. The cultivation and improvement of the plantation rubber crop. Res. Archives of the Rubber Research Insitute of Malaya. Document No. 29, pp. 1–30.