Digangi JP, Boyle ES, Karl T, Harley P, Turnipseed A, Kim S, Cantrell C, Maudlin, R. L. III, Zheng W, Flocke F, et al. First direct measurements of formaldehyde flux via eddy covariance: implications for missing in-canopy formaldehyde sources. Atmospheric Chemistry and Physics. 2011;11:10565-10578.