Calculation of Vibration–Rotation Energy Levels: Symmetry, Transformations, Open–Shell Molecules. Effective Hamiltonians for Flexible or Floppy Molecules. Rovibrational Line Intensities and Lineshapes: Linear and Non–Linear Spectroscopy. The Experimental Measurement of Infrared Spectra. Analysis of the Vibration–Rotation Bands of Linear Molecules. Analysis of Symmetric and Spherical Rotor Spectra. Asymmetric Rotor Bands. Electric and Magnetic Resonance Spectroscopy. Laser Spectroscopy of Free Radicals, Ions and Weakly Bound Molecules. Spectroscopy of the Earth′s Atmosphere: Interplay Between High–Resolution Laboratory Spectroscopy and Remote Sensing. Astrophysical Spectra. Indexes.