Columbia subject headings:
Harvard subject headings:
Businesspeople--Germany--Hamburg--Biography.
Ertel, Julius Carl, 1845-1922.
Industrialists--Germany--Hamburg--Biography.
Metal trade--Germany--Hamburg--History--20th century.
Princeton subject headings:
Businesspeople--Germany--Hamburg--Biography.
Ertel, Julius Carl, 1845-1922.
Industrialists--Germany--Hamburg--Biography.
Metal trade--Germany--Hamburg--History--20th century.