@article{Makadia_Karavadiya_Kaneria_2019, title={Graceful centers of graceful graphs and universal graceful graphs.}, volume={38}, url={https://www.revistaproyecciones.cl/index.php/proyecciones/article/view/3574}, abstractNote={In this paper we define graceful center of a graceful graph. We proved any graph G which admits α-labeling has at least four graceful centers. We also defined a new strong concept of universal graceful graph. Some results on ring sum of two graphs for their graceful labeling are proved.}, number={2}, journal={Proyecciones (Antofagasta, On line)}, author={Makadia, H. M. and Karavadiya, H. M. and Kaneria, V. J.}, year={2019}, month={May}, pages={305-314} }