Vargas-Vargas, M., Meseguer-SantamarÃa, M., Mondéjar - Jiménez, J., & Mondéjar - Jiménez, J. "Environmental Protection Expenditure for Companies: A Spanish Regional Analysis", International Journal of Environmental Research, 4, 3, 2010, 373-378. doi: 10.22059/ijer.2010.1