http://www.arkat-usa.org/get-file/45154/
I. Alkorta, G. Sanchez-Sanz, C. Trujillo, J. Elguero, R. M. Claramunt
A theoretical study of the parent NH-benzazoles (benzimidazoles,indazoles and benzotriazoles): geometries, energies, acidity and basicity, NMR properties and molecular electrostatic potentials