B.D. Acharya and .M. Hegde, Arithmetic graphs, J. Graph Theory 14 (1990), no. 3, 275--299.
J.A. Gallian, A dynamic survey of graph labeling, Electron. J. Combin. 16 (2010) 1--246.
S.M. Hegde, On $(k,d)$-graceful graphs, J. Combin. Inform. System Sci. 25 (2000), no. 1-4, 255--265.
B. Yao, H. Cheng, M. Yao and M. Zhao, A note on strongly graceful trees, Ars Combin. 92 (2009) 155--169.
X. Zhou, B. Yao and X. Chen, Every lobster is odd-elegant, Inform. Process. Lett. 113 (2013), no. 1-2, 30--33.
X. Zhou, B. Yao, X. Chen and H. Tao, A proof to the odd-gracefulness of all lobsters, Ars Combin. 103 (2012) 13--18.