[3] A. Bowling and P. Zhang, Absolutely and conditionally zonal graphs, Electronic J. Math. 4 (2022), 1–11.
[5] F. Eskandari, H. Arianpoor, and M. Habibi, Zonal labeling of halin graphs, submitted.
[7] P. Kovář, Magic labelings of graphs, Ph.D. thesis, VŠB–Technical University of Ostrava, 2004.