Spectra of the prominent lines of CH₃CN (J = 14–13; left panels) and CH₃OH (right panels) extracted at the position of the 1.2-mm peak for each of the four continuum sources B, A1, A2 and A3 (from top to bottom panels, respectively). The spectra are shown as brightness temperature vs. rest frequency. The transitions of the two molecular species (see Table 2) are labeled in the upper panels.