Kumra, V. K., Nag, P., & Singh, J. (1997). Geography and environment. Concept Pub.
Lua i Stíl Chicago (17ú heag.)Kumra, V. K., Prithvish Nag, agus Jagdish Singh. Geography and Environment. New Delhi: Concept Pub, 1997.
Lua MLA (9ú heag.)Kumra, V. K., et al. Geography and Environment. Concept Pub, 1997.
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