1. American Public Transit Association, APTA (1992a) 1991 Transit Fact Book. Washington, DC.
2. American Public Transit Association, APTA (1992b) Transit data of earlier data books, personal communication, Washington, DC.
3. Asin, R. H. (1983) Person Trip Characteristics—1977 NPTS. U.S. Department of Transportation, Federal Highway Administration, Report No. 11, Washington, DC., U.S.A.
4. Australian Bureau of Statistics, ABS (1965, 1970, 1975, 1980, 1985, 1990, 1992) Year Book Australia. Canberra.
5. Biro Pusat Statistic, BPS (1986, 1993) Statistical Yearbook of Indonesia. Central Bureau of Statistics, Jakarta, Indonesia.