Sky distributions of the various samples used in this study. Black dots are 1000 randomly selected sources from the deep IRAC-selected photo-z catalogs at 2 < z < 3 for clarity. We require all samples to be located inside the central black boxes in order to avoid searching for neighbors outside of the sky area coverage. HLIRGs at 2 < z < 3, redshift-matched quasars and SMGs (only in the LH field) are plotted as red circles, blue squares, and cyan squares respectively.