1. Externalitiy;Buchanan;Economica,1962
2. The problem of social cost;Coase;Journal of Law and Economics,1960
3. The problem of externality;Dahlman;Journal of Law and Economics,1979
4. Department of the Environment Transport and the Regions, 1998. The government's consultation on developing an integrated transport policy: a report, DETR.
5. European Union, Cordis, Transport RTD Programme, 1999. SORT-IT/MINIMISE Joint Final Report; www.cordis.lu/transport.