Boehm, R. G., Armstrong, D. G., & Hunkins, F. P. Geography: The world and its people.
Chicago-viite (17. p.)Boehm, Richard G., David G. Armstrong, ja Francis P. Hunkins. Geography: The World and Its People.
MLA-viite (8. p.)Boehm, Richard G., et al. Geography: The World and Its People.
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