Selected transitions of MF detected in different wavebands and sources: (a) 0.9 mm waveband, source 18089-1732; (b) 2 mm, G31.41+0.31; (c) 3 mm, G31.41+0.31. The LTE synthetic spectrum obtained in the line fitting procedure with MADCUBA (see Sect. 4) is overplotted in red. See Tables D.1–D.3 for a list of the brightest lines detected for each molecule in each waveband and their spectroscopic parameters.