The term race is often used loosely to indicate groups of men differing in appearance, language or culture. As here understood it applies solely to the biological grouping of human types. On account of the lack of sharp lines of demarcation the attempts at classification, based on varying characteristics, have not let to a generally accepted system.
Source: The Encyclopaedia of the Social Sciences, Vol VIII (NY: Macmillan, 1930-35): 25-36
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