 Boas also contributed greatly to the foundation of linguistics as a science in the United States.He published many descriptive studies of Native American languages, and wrote on theoretical difficulties in classifying languages, and laid out a research program for studying the relations between language and culture which his students such as Edward Sapir, Paul Rivet, and Alfred Kroeber followed.His 1889 article "On Alternating Sounds", however, made a singular contribution to the methodology of both linguistics and cultural anthropology.