Boehm, R. G., & Richard G. Boehm; Francis P. Hunkins; David G. Armstrong. Exploring our world: People, places, and cultures. Columbus, Ohio: McGraw-Hill/Glencoe.

Boehm, Richard G., و Richard G. Boehm; Francis P. Hunkins; David G. Armstrong. Exploring Our World: People, Places, and Cultures. Columbus, Ohio: McGraw-Hill/Glencoe.

Boehm, Richard G., و Richard G. Boehm; Francis P. Hunkins; David G. Armstrong. Exploring Our World: People, Places, and Cultures. Columbus, Ohio: McGraw-Hill/Glencoe.