Hornberger, Wolfgang S., Louis E. Keefer, and William R. McGrath. Transportation and Traffic Engineering Handbook. 2d ed. Englewood Cliffs, N.J.: Prentice-Hall, 1982.

Hornberger, Wolfgang S., Louis E. Keefer, and William R. McGrath. Transportation and Traffic Engineering Handbook. 2d ed. Englewood Cliffs, N.J.: Prentice-Hall, 1982.