Srivastava , Ambrish K.Pandey , Anoop K.Gangwar , Shashi K. and Misra , Neeraj. (2014). Structural, Vibrational and Electronic Properties of cis and trans Conformers of 4-Hydroxy-l-Proline: A Density Functional Approach.
            <i>Journal of Atomic and Molecular Sciences</i>. <i>5</i> (4).
            279-288.
         doi:10.4208/jams.022214.041814a