1. Graham, R.L., Sloane, N.J.A.: On additive bases and harmonious graphs. SIAM J. Algebr. Discrete Methods 1, 382–404 (1980)
2. Liu, B.: Strongly harmonious equation of graph with application. J. Xinjiang Univ. 1, 30–34 (1988)
3. Liang, Z.: Harmoniousness of quadrilateral cactus. J. Eng. Math. 1, 131–134 (2001)
4. Gallian, J.A.: A dynamic survey of graph labeling. Electron. J. Comb. 5, 1–148 (2005), DS#6
5. Youssef, M.Z.: Two general results on harmonious labeling. Ars Comb. 68, 225–230 (2003)