Top: minimal spanning tree of the YSOs overplotted on a color composite image of the CrW region (WISE 22 μm (red), Hα band (green), and V band (blue) images). WR 22 is situated in the center. The white circles connected with dotted lines, and black circles connected with solid lines are the branches that are larger and smaller than the basic critical length, respectively. The identified ten cluster cores are encircled with yellow color and labeled with A to J. Bottom: two zoomed images of YSO cores, C and E, are shown in the lower left and right panels, respectively (see text for detail).