Wang , Zhong-Jie and Fan , Chao-Yang. (2011). Nonclassical Properties and Generation of Superposition State of Excited Coherent States of Motion of Trapped Ion.
            <i>Journal of Atomic and Molecular Sciences</i>. <i>2</i> (4).
            352-359.
         doi:10.4208/jams.010811.022311a