Class I ($\alpha_{3.6-8.0} > -0.3$), Class II ($-0.3 > \alpha_{3.6-8.0} > -1.6$), and Class III ($-1.6> \alpha_{3.6-8.0} > -2.56$)) [e.g., @lada06]. We select additional 22 YSOs (14 Class I and 8 Class II) using this scheme, which are plotted in Figure \[fig10\]c. These selected YSOs are not overlapped with that YSOs shown in Figure \[fig10\]a. Photometric information of all the selected YSOs is given in Table \[tab3\]. Figure \[fig10\]d shows the overlay of the selected YSOs on the [*Spitzer*]{} ratio map of 4.5 $\mu$m/3.6 $\mu$m emission, revealing the association of YSOs with the bright regions due to an excess of 4.5 $\mu$m emission (or outflow activities; see Section \[subsec:u1\]).

Figure \[fig11\]a displays a surface density contour map of 135 YSOs distributed in the area shown in Figure \[fig10\]c. The surface density contours of YSOs are shown with the levels of 5, 10, 15, 20, 30, 40, 60, and 85 YSOs/pc$^{2}$, suggesting the intense ongoing SF activities in the selected site. In Figure \[fig11\]a, the [*Herschel*]{} column density contours (in red), the infrared shell (in cyan), and the diffuse H$\alpha$ emission contour (in blue) are also highlighted in the surface density contour map. We employed the nearest-neighbour (NN) method to estimate 