Chillón, P., Ortega, F., Ruiz, J., Pérez, I., Martín-Matilla, M., Valtuea, J., et al. (2009). Socio-economic factors and active commuting to school in urban Spanish adolescents The AVENA Study. European Journal of Public Health 19, 470-476. doi10.1093/eurpub/ckp048 - References - Scientific Research Publishing