Columbia subject headings:
Sudan--History--1821-
Harvard subject headings:
Giegler, Carl Christian, 1844-1921.
Sudan--Officials and employees--Biography.
Telegraphers--Biography.
Telegraphers--Sudan--Biography.
Princeton subject headings:
Giegler, Carl Christian, 1844-1921.
Sudan--Officials and employees--Biography.
Telegraphers--Sudan--Biography.