(1960). Highway statistics 1960. Washington, D.C: United States goverment printing office.
Παραπομπή Chicago StyleHighway Statistics 1960. Washington, D.C: United States goverment printing office, 1960.
Παραπομπή MLAHighway Statistics 1960. Washington, D.C: United States goverment printing office, 1960.
Πρόσοχή: Οι παραπομπές μπορεί να μην είναι 100% ακριβείς.