9Mao B H, Chert H B. Sustainability analysis of Chinese transport policy [J]. International Journal of Sustainable Development and World Ecology, 2001, 8(4) :323-336.
10Fakayode S O, Olu-Owolabi B L Heavy metal contamination of roadside topsoil in Osogho, Nigeria: its relationship to traffic density and proximity to highways [J]. Environmental Geology, 2003, 44(2) :150-157.