Warning signs and advisory speed signs :
reevaluation of practice /
prepared by Helmut T. Zwahlen (Department of Industrial and Systems Engineering, College of Engineering and Technology, Ohio University).

APA Citation

Zwahlen, H. T., United States. Federal Highway Administration., Ohio. Dept. of Transportation., Ohio University. Dept. of Industrial and Systems Engineering. (1983). Warning signs and advisory speed signs: reevaluation of practice. Athens, Ohio: The Department .

MLA Citation

Zwahlen, Helmut T, United States. Federal Highway Administration, Ohio. Dept. of Transportation, and Ohio University. Dept. of Industrial and Systems Engineering. Warning Signs And Advisory Speed Signs: Reevaluation of Practice. Athens, Ohio: The Department , 1983.

Warning: These citations may not always be complete (especially for serials).