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A scene from a kelp forest off the west coast of North America. Like terrestrial forests, kelp fores
The Dall sheep, Ovis dalli, a mountain sheep of far northern North America, was the subject of one o
Distribution of glaciers in North America (a) in the late twentieth century, and (b) 18,000 years ag
Vitamin Deficiency
The United States in the Caribbean and Central America
Diseases Common to the Elderly