1. ACEM Association Des Constructeurs Européens de Motocycles. Market Data. Available at: https://www.acem.eu/Market-Data 2019.
2. EUROPEAN COMMISSION. Directorate General for Mobility and Transport EU Transport in Figures: Statistical Pocketbook; 2018; ISBN 978-92-79-73951-4.
3. Changes in the Market of Two and Three-wheeled Motor Vehicles in Europe at the Beginning of the 21st Century
4. Particulate emissions from L-Category vehicles towards Euro 5
5. NTZIACHRISTOS, L., VONK, W.A., PAPADOPOULOS, G. et al. Effect study of the environmental step Euro 5 for L-category vehicles. European Commission. 2017, ISBN 978-92-79-70203-7.