1. Austin, R.B., J., Bingham, R.D., Blackwell, L.T., Evans, M.A., Ford, C.L., Morgan & M., Taylor, 1980. Genetic improvements in winter wheat yields since 1900 and associated physiological changes. J. agric. Sci., Camb. 94: 675–689.
2. Beirnaert, A. & R. Vanderweyen, 1941. Contribution a l'étude génétique et biométrique des variétés d'Elaeis guineensis Jacquin. Publ. Inst. Nat. Etude agron. Congo Belge, Sér. Sci., 27, 101 pp.
3. Blaak, G., L.D., Sparnaaij & T., Menendez, 1963. Breeding and inheritance in the oil palm (Elaeis guineensis Jacq.) II. Methods of bunch quality analysis. J. West Afr. Inst. Oil Palm Res. 4: 146–155.
4. Breure, C.J., 1988. The effect of different planting densities on yield trends in oil palm. Expl Agric. 24: 37–52.
5. Breure, C.J. & R.H.V., Corley, 1983. Selection of oil palms for high density planting. Euphytica 32: 177–186.