^Daintith, John (2008). "tar". A Dictionary of Chemistry (6th ed.). Oxford University Press. doi:10.1093/acref/9780199204632.001.0001. ISBN9780199204632. "Tar: Definition". Miriam Webster. Retrieved 14 March 2013. "a dark brown or black bituminous usually odorous viscous liquid obtained by destructive distillation of organic material (such as wood, coal, or peat)".
"tar and pitch" (6th ed.). The Columbia Electronic Encyclopedia. Retrieved 14 March 2013. "tar and pitch, viscous, dark-brown to black substances obtained by the destructive distillation of coal, wood, petroleum, peat and certain other organic materials. "