Columbia subject headings:
Parthia--Foreign relations--Rome.
Rome--Foreign relations--Iran--Parthia.
Harvard subject headings:
Customary law (Roman law)
International law (Roman law)
Parthia (Iran)--Foreign relations--Rome.
Parthia--Foreign relations--Rome.
Rome--Foreign relations--Iran--Parthia.
Princeton subject headings:
Parthia (Iran)--Foreign relations--Rome.
Rome--Foreign relations--Iran--Parthia.