Tran, Q. D., S. C. Ho, V. H. Dao, and T. M. Duc. “Higher-Order Nonclassicality in Superposition of Three-Mode Photon-Added Trio Coherent State”. Communications in Physics, vol. 32, no. 2, Mar. 2022, p. 141, doi:10.15625/0868-3166/16508.