Two-color image: the ¹³CO emission integrated between 53 and 61 km s^-1 is presented in green, and the 8 μm emission, in red. For sharper contrast, the ¹³CO emission scale is displayed in square root and bordered by a white contour. The yellow crosses indicate the position of the intrinsically red sources, i.e., sources satisfying the condition m_4.5 − m_8.0 + ε ≥ 1. We labeled the sources that appear to be related to the molecular gas around G35.6.