Effect of planting density on growth, yield, yield related factors and profitability of rubber (Hevea brasiliensis) Muell. Arg. - Rodrigo V H L; Kodikara P B; Nugawela A; Pathirathne L S S; Samaranayake A C I; Waidyanatha U P de S; Weeralal J L K (Journal of the Rubber Research Institute of Sri Lanka, 1995)