1. Bates, J. J. and Roberts, M. 1983. “Data collection for choice models based on hypothetical transport alternatives,”. paper presented at the New Survey Methods in Transport, 2nd International Conference. 1983, Australia.
2. Borjesson, M. 1989. “Public transport for everyone: a summary of the results of research and development projects concerning disabled people and transport facilities supported by the Swedish Transport Research Board.”. Stockholm: Swedish Transport Research Board. (ISBN 91 87246 38 4)