Não informado. (1966). Summary of progress. National Cooperative Highway Research Program.
Chicago-viite (17. p.)Não informado. Summary of Progress. Washington: National Cooperative Highway Research Program, 1966.
MLA-viite (8. p.)Não informado. Summary of Progress. National Cooperative Highway Research Program, 1966.
Varoitus: Nämä viitteet eivät aina ole täysin luotettavia.