Boyce, R. R. (1982). Geographic perspectives on global problems: An introduction to geography. John Wiley and Sons.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रBoyce, Ronald Reed. Geographic Perspectives on Global Problems: An Introduction to Geography. John Wiley and Sons, 1982.
एमएलए (9वां संस्करण) प्रशस्ति पत्रBoyce, Ronald Reed. Geographic Perspectives on Global Problems: An Introduction to Geography. John Wiley and Sons, 1982.
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