Stopping neccecary - Old Greek stop sign according to road traffic codex 1962 (KOK 1962). The exact same sign was used almost everywere in Europe before the Vienna Convention. Although it was suggested in the Convention, most countries who signed, today use tho octagonal sign used almost worldwide. In Greece, it was used until 1974, when it was replaced by the octagonal sign R-2, but it was still temporary used until 1978 as Pd-2.
Replica from 1961 Greek Highway Code
Peeperman