Hobbs, F.D.
Pergamon Press, 1974
Buku Teks
Artikel Jurnal
Institute of Traffic Engineers ; John E. Baerwald, editor, associate editors, Matthew J. Huber, Louis E. Keefer
Prentice-Hall, 1976
Buku Referensi
edited by Wolfgang S. Homburger, Louis E. Keefer and William R. McGrath
Prentice-Hall, 1994
Buku Referensi
Currin, Thomas R.
Brooks/Cole, 2001
Buku Teks