Xue, Y.Q., Brandt, W.N., Luo, B., Rafferty, D.A., Alexander, D.M., Bauer, F.E., Lehmer, B.D., Schneider, D.P., Silverman, J.D., "Color-magnitude relations of active and non-active galaxies in the Chandra Deep Fields : high-redshift constraints and stellar-mass selection effects", Astrophysical Journal, 2010