1. Ali R.M., Nagpal S., Ravichandran, V.: Second-order differential subordination for analytic functions with fixed initial coefficient. Bull. Malays. Math. Sci. Soc. (2) 34(3), 611–629 (2011)
2. Kanas S., Lecko A., Stankiewicz J.: Differential subordinations and geometric means. Compl. Var. 44. Theor. Appl. 28, 201–209 (1996)
3. Kanas S., Stankiewicz J.: Arithmetic means with reference to convexity conditions, Bull. Soc. Sci. Lett. Łódź 47, Ser. Rech. Deform. 24, 73–82 (1997)
4. Kanas, S., Lecko, A.: Univalence criteria connected with arithmetic and geometric means, II. Folia Sci. Univ. Tech. Resov. 20, 49–59 (1996)
5. Kanas S., Lecko A.: Univalence criteria connected with arithmetic and geometric means, II. In: Proceedings of the Second International Workshop of Transform Methods and Special Functions, Varna ’96, pp. 201–209. Bulgarian Academy of Sciences, Sofia (1996)