Tautomerism and infrared spectra of 2-thiopurine: an experimental matrix isolation and theoretical ab initio and density functional theory study.
Stepanenko T, Lapinski L, Nowak MJ, Kwiatkowski JS, Leszczynski J. Tautomerism and infrared spectra of 2-thiopurine: an experimental matrix isolation and theoretical ab initio and density functional theory study. Spectrochim Acta A Mol Biomol Spectrosc. 2001 Feb; 57(2):375-83.