Columbia subject headings:
Harvard subject headings:
German Americans--History--19th century
German Americans--History--20th century.
Germany, Northern--Emigration and immigration--History.
Immigrants--United States--History--19th century
Immigrants--United States--History--20th century
United States--Emigration and immigration--History.
Princeton subject headings:
German Americans--History--19th century.
German Americans--History--20th century.
Germany, Northern--Emigration and immigration.
United States--Emigration and immigration.