1. Ayel, J., Favaron, O.: Helms are Graceful in Progress in Graph Theory (Waterloo Ont., 1982), pp. 89–92. Academic Press, Toronto (1984)
2. Deb P., Limaye N.B.: On Harmonious labeling of some cycle related graphs. Ars Comb. 65, 177–197 (2002)
3. Delorme C., Maheo M., Thuillier H., Koh K.M., Teo H.K.: Cycles with a chord are graceful. J. Graph Theory 4, 409–415 (1980)
4. Frucht R.: Graceful numbering of wheels and related graphs. Ann. N.Y. Acad. Sci. 319, 219–229 (1979)
5. Gallian Joseph, A.: A dynamic survey of graph labeling, 17th edn. Electron. J. Comb. (2014)