Passage: Relying on money donated by neighbors, Du Bois attended Fisk University, a historically black college in Nashville, Tennessee, from 1885 to 1888. His travel to and residency in the South was Du Bois's first experience with Southern racism, which at the time encompassed Jim Crow laws, bigotry, suppression of black voting, and lynchings; the lattermost reached a peak in the next decade. After receiving a bachelor's degree from Fisk, he attended Harvard College (which did not accept course credits from Fisk) from 1888 to 1890, where he was strongly influenced by his professor William James, prominent in American philosophy. Du Bois paid his way through three years at Harvard with money from summer jobs, an inheritance, scholarships, and loans from friends. In 1890, Harvard awarded Du Bois his second bachelor's degree, cum laude, in history. In 1891, Du Bois received a scholarship to attend the sociology graduate school at Harvard.In 1892, Du Bois received a fellowship from the John F. Slater Fund for the Education of Freedmen to attend the University of Berlin for graduate work. While a student in Berlin, he traveled extensively throughout Europe. He came of age intellectually in the German capital while studying with some of that nation's most prominent social scientists, including Gustav von Schmoller, Adolph Wagner, and Heinrich von Treitschke. He wrote about his time in Germany: "I found myself on the outside of the American world, looking in. With me were white folk—students, acquaintances, teachers—who viewed the scene with me. They did not always pause to regard me as a curiosity, or something sub-human; I was just a man of the somewhat privileged student rank, with whom they were glad to meet and talk over the world; particularly, the part of the world whence I came." After returning from Europe, Du Bois completed his graduate studies; in 1895 he was the first African American to earn a Ph.D. from Harvard University.

Question: Which prominent  social scientists did Du Bois work with?
Gustav von Schmoller, Adolph Wagner, and Heinrich von Treitschke