Bancroft, George. A History of the United States, from the Discovery of the American Continent. Little, Brown, 1840. 

This was the old way of viewing languages. “It has been asked if our Indians were not the wrecks of more civilized nations. Their language refutes the hypothesis”. George Bancroft wrote that the language of the Indians was so perverse as compared to Greek or Latin that the natives of this land could not comprehend to the level that speakers of those languages could.

Sapir, Edward. Language: An Introduction to the Study of Speech. Hart-Davis, 1921.  

The change in how languages are viewed. Culture, race, and language may be related but that is through historical change and not from the limits of the language. Language is not limited by race. Language does not limit culture. This was perhaps the most influential book in all of linguistics. Sapir describes how different language structures work across language groups worldwide, from French to Sanskrit to Turkish to Hebrew. He spends the 10th chapter describing language families and relationships between them and culture/races to unintertwine the concepts and show that the concepts do not necessarily interact with each other.

Sapir, Edward. “A Bird’s-Eye View of American Languages North of Mexico.” Science, vol. 54, no. 1400, 1921, pp. 408–408., doi:10.1126/science.54.1400.408.

This short journal article by Sapir proposes a taxonomic relation between Native American languages. It is an early example of identifying linguistic similarities in differing languages on this continent and was crucial in convincing others to take stock in Native American languages as serious items of study and research.

Rivers, W.H.R. “Primitive Color Vision.” Popular Science, vol 59, pp. 44-58

This article was written after visiting the Torres Strait Islands wherein he observed natives who only had three to four names for colors in their language. He concluded that “the development of their color language, corresponds with the order in which they would be placed on the ground of their general and cultural development.” He, like many others at the time, thought that the natives were colorblind and could only see these three or four colors, therefore proving their inferiority.

Berlin, Brent, and Paul Kay. “Basic Color Terms: Their Universality and Evolution.” International Journal of American Linguistics, vol. 37, no. 4, 1971, pp. 257–270., doi:10.1086/465174.