1. Anderson, T.W. 1958. Introduction to multivariate statistical analysis. John Wiley & Sons, New York.
2. Andrew, I.A. & J. Burley. 1972. Variation of wood quality of Pinus merkusii Jungh. and de Vriese; five trees of Burma provenance grown in Zambia Rhod. J. Agric. Res. 10: 183–202.
3. Bailey, I.W. & H.B. Shephard. 1915. Sanio’s laws for the variation in size of coniferous tracheids. Bot. Gaz. 60: 66–71.
4. Balan Menon, P.K. 1957. Microscopic key for the identification of commercial timbers. Malay Forester 20: 162–164.
5. Beversluis, J.R. 1943. De micrografische identificatie van conifere houtsoorten. Meded. Landb. Hogesch. Wageningen 47 /2: 39 pp.