Links:
[1] http://admin.indiaenvironmentportal.org.in/feature-article/metro-rail-systems
[2] http://admin.indiaenvironmentportal.org.in/category/author/c-ramachandraiah
[3] http://admin.indiaenvironmentportal.org.in/category/journal/economic-and-political-weekly
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/transport
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/public-transport
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/urban-transport
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/rail-transport
[8] http://admin.indiaenvironmentportal.org.in/category/thesaurus/metro
[9] http://admin.indiaenvironmentportal.org.in/category/thesaurus/india
[10] http://admin.indiaenvironmentportal.org.in/category/thesaurus/andhra-pradesh