The integrated intensities of the ¹²CO maps of integrated area toward a) MON R2, b) S156, c) DR17/L906, and d) M17/M18. The color-scale maps are the same as Fig. 1. a) For the MON R2 region: ¹²CO contour levels are from 12.80 to 34.14 in steps of 4.27 K km s^-1. b) For the S156 region: ¹²CO contour levels are from 12.63 to 33.69 in steps of 4.21 K km s^-1. c) For the DR17/L906 region: ¹²CO contour levels are from 12.72 to 39.26 in steps of 4.91 K km s^-1. d) For the M17/M18 region: ¹²CO contour levels are from 29.34 to 78.24 in steps of 9.78 K km s^-1.