"अलकतरा": अवतरणों में अंतर

* [[चारकोल]] या काठकोयला

* [[कोक]]

* [http://www.osha.gov/SLTC/coaltarpitchvolatiles/index.html ''Coal Tar Pitch Volatiles'' by OSHA]

* [http://pubs.acs.org/doi/full/10.1021/es803118b?cookieSet=1 ''Parking lots create sticky pollution problem'' by Erica Engelhaupt Environmental Science and Technology]