Venn diagram illustrating the distributions of ATLASGAL clumps (black numbers) that are in association with mm-RRL detection, radio continuum sources (only considering large continuum surveys for clumps without mm-RRL detection, while the number of radio sources with mm-RRL is based on complete, individual searches), and WISE 22 μm emission (only considering association with WISE 22 μm point sources). In addition, average integrated fluxes of total Hnα and 6 cm radio continuum are given as red and blue numbers in Jy km s^-1 and mJy, respectively. The star (^∗) indicates that these 33 sources are saturated in WISE 22 μm emission and the dagger (^†) indicates that contaminated sources have been included. The numbers in parentheses represent 8 mid-IR dark sources among the 27 clumps with only mm-RRL and 8 potential H ii candidates among the 17 clumps with both the mm-RRL and the WISE 22 μm point source.