M. Jessy, A. Sasidharan Nair, M. M. Bai, P. Rajendran, and K. Punnoose, “Self-sustainability of phosphorus cycle in rubber (Hevea brasiliensis) plantations: Annual recycling through litter and removal through latex”, JPC, vol. 37, no. 3, pp. 177–184, Oct. 2009.