Columbia subject headings:
Harvard subject headings:
Military history, Ancient
Rome--Army--Communication systems--History.
Rome--Army.
Rome--History, Military.
Signals and signaling--Germany--History.
Signals and signaling--Great Britain--History.
Signals and signaling--History.
Signals and signaling--Rome.
Princeton subject headings:
Military history, Ancient.
Rome--Army.
Rome--History, Military.
Signals and signalling--Rome.