1. 1) State of Illinois; County of Cook; City of Chicago: Chicago Area Transportation Study. Final Reports. Vol. 1 Appendix. p. 107, 1962.
2. 2) Bureau of public Roads and National Committee on Urban Transportation: Origin-Destination and Land Use, Rrocedure Manual 2 A; pp. 13-15, Public Administration Service. 1958.
3. 3) Committee on Tokyo Metropolitan Area Person Trip Survey: Reports on Tokyo Metropolitan Area Comprehensive Transportation Study. p. 230, Ministry of Construction et al., 1970, (In Japanese).
4. 4) Miyazawa, K.: Modern Statistics. pp. 211-213, Baifu-kan, 1962, (In Japanese).
5. 5) Nakayama, I. et al.: Modern Statistics Dictionary, pp. 451-455, Toyo Keizai Sinposha, 1962, (In Japanese).