Pandey , SaurabhSrivastava , Ambrish KumarPandey , Anoop and Misra , Neeraj. (2014). Theoretical Study of Small Niobium Sulphide Clusters, $Nb_nS_m (m,n=1, 2)$.
            <i>Journal of Atomic and Molecular Sciences</i>. <i>5</i> (3).
            231-237.
         doi:10.4208/jams.040214.062114a