Coles, P. A., Ovsyannikov, R. I., Polyansky, O. L. , Yurchenko, S. N., Tennyson, J., "Improved potential energy surface and spectral assignments for ammonia in the near-infrared region", Journal of Quantum Spectroscopy and Radiative Transfer219, 199-212 (2018). [link to article][18CoOvPo.NH3]