found: Work cat.: Color tests for differentiating heartwood and sapwood of certain oaks, pines, and Douglas-fir, 1954.
found: Answers.com, accessed Aug. 25, 2005(sapwood: The newly formed outer wood located just inside the vascular cambium of a tree trunk and active in the conduction of water. Sapwood is usually lighter in color than heartwood)
found: McGraw-Hill dictionary of scientific and technical terms, 2003(sapwood: the younger, softer, outer layers of a woody stem, between the cambium and heartwood. Also known as alburnum)
found: Song, Hong-keun. Chemistry of phenolic stains in Douglas-fir sapwood, 1987.
found: Differences between heartwood and sapwood, 1936.