Gelencser, A., May, B., Simpson, D., Sánchez Ochoa, A., Kasper-Giebl, A., Puxbaum, H., Caseiro, A., Pio, C., & Legrand, M. (2007). Source apportionment of PM2.5 organic aerosol over Europe: Primary/secondary, natural/anthropogenic, and fossil/biogenic origin. Journal of Geophysical Research: Atmospheres, 112(D23S04). https://doi.org/10.1029/2006jd008094