Pegrum, D. F. (1968). Transportation economics and public policy. Richard D. Irwin.
Lua i Stíl Chicago (17ú heag.)Pegrum, Dudley F. Transportation Economics and Public Policy. Richard D. Irwin, 1968.
Lua MLA (8ú heag.)Pegrum, Dudley F. Transportation Economics and Public Policy. Richard D. Irwin, 1968.
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