1. Battle, J., Harary, F., Kodama, Y., Youngs, J.W.T.: Additivity of the genus of a graph. Bull. Am. Math. Soc. 68, 565–568 (1962)
2. Berkovič, J.G.: $$p$$-groups of finite order. Sibirsk. Mat. Ž. 9, 1284–1306 (1968)
3. Bhuniya, A.K., Bera, S.: Normal subgroup based power graphs of a finite group. Comm. Algebra 45(8), 3251–3259 (2017)
4. Doostabadi, A., Farrokhi, D.G.M.: Embeddings of (proper) power graphs of finite groups. Algebra Discrete Math. 24(2), 221–234 (2017)
5. Frobenius, G.: Verallgemeinerung des Sylow’schen Satzes: Über auflösbare Gruppen II. Von G. Frobenius. Reichsdr (1895)