1. Introduction
2. The sources
3. Observations and data reduction
3.1. Observations
3.2. Data reduction
3.3. Data combination
4. Analysis and results
4.1. Line detection and identification
4.2. Line Variability
4.3. Morphological diversity
4.4. Column density and rotation temperature estimates
4.5. Abundance estimates
4.6. Isotopic ratios
5. Discussion
6. Summary and conclusions