DiGangi, JP, Henry SB, Kammrath A, Boyle ES, Kaser L, Schnitzhofer R, Graus M, Turnipseed A, Park JH, Weber RJ et al..  2012.  Observations of glyoxal and formaldehyde as metrics for the anthropogenic impact on rural photochemistry. Atmospheric Chemistry and Physics. 12(20):9529-9543.