1. Reference1: S. Albeverio, B. A. Omirov and I. S. Rakhimov, {\em Classification of 4-dimensional nilpotent complex Leibniz algebras}, Extracta mathematicae \textbf{21}(3):197-210, 2006.
2. Reference2: Sh. A. Ayupov and B. A. Omirov, {\em On 3-dimensional Leibniz algebras}, Uzbek. Math. Zh. \textbf{1}, 9-14, 1999.
3. Reference3: D. Barnes, {\em Some theorems on Leibniz algebras}, Comm. Algebra \textbf{39}(7), 2463-2472, 2011. DOI: 10.1080/00927872.2010.489529
4. Reference4: A. Bloh, {\em On a generalization of Lie algebra notion}, Math. in USSR Doklady \textbf{165}(3), 471-473, 1965.
5. Reference5: J.-M. Casas, M.-A. Insua, M. Ladra and S. Ladra, {\em An algorithm for the classification of 3-dimensional complex Leibniz algebras}, Linear Algebra Appl. \textbf{9}, 3747-3756, 2012. DOI: 10.1016/j.laa.2011.11.039