Spectra with the wavelength range intercept to 4400–9000 Å. The LAMOST spectra of some common sources are plotted with black lines. The red and yellow lines are the result of their convolution to 50 resolution. The blue and green lines are the Gaia spectra. In the bottom panel, the light gray shaded areas pick out the peaks and the red dashed lines in the bottom panels mark several obvious CN absorption line locations.