Não informado. (1968). Research Results Digest. National Cooperative Highway Research Program.
Chicago-Zitierstil (17. Ausg.)Não informado. Research Results Digest. Washington: National Cooperative Highway Research Program, 1968.
MLA-Zitierstil (8. Ausg.)Não informado. Research Results Digest. National Cooperative Highway Research Program, 1968.
Achtung: Diese Zitate sind unter Umständen nicht zu 100% korrekt.