Changeable message signs / Conrad L. Dudek
Dudek, Conrad L.
Changeable message signs / Conrad L. Dudek - Washington, D.C. : TRB - 57 p. - Synthesis of highway practice ; 237 / Transportation Resear-ch Board .
Changeable message signs / Conrad L. Dudek - Washington, D.C. : TRB - 57 p. - Synthesis of highway practice ; 237 / Transportation Resear-ch Board .