Private bus operators own a bulk of Delhi's public transport buses
Links:
[1] http://admin.indiaenvironmentportal.org.in/news/living-borrowed-time
[2] http://admin.indiaenvironmentportal.org.in/category/author/asha
[3] http://admin.indiaenvironmentportal.org.in/category/newspaper/down-earth
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/cng