League of Nations. Organisation for Communications and Transit, European Conference on Road Traffic, & European Conference on Road Traffic. (1933). Road signalling: Recommendations and prescriptive rules adopted by the European Conference on Road Traffic and the Permanent Committee on Road Traffic. League of Nations.
Cita Chicago (17th ed.)League of Nations. Organisation for Communications and Transit, European Conference on Road Traffic, i European Conference on Road Traffic. Road Signalling: Recommendations and Prescriptive Rules Adopted by the European Conference on Road Traffic and the Permanent Committee on Road Traffic. [Geneva: League of Nations, 1933.
Cita MLA (8th ed.)League of Nations. Organisation for Communications and Transit, et al. Road Signalling: Recommendations and Prescriptive Rules Adopted by the European Conference on Road Traffic and the Permanent Committee on Road Traffic. League of Nations, 1933.