Ling Zhu, “The Natural Approaches of Shafer-Fink Inequality for Inverse Sine Function”, Mathematics, 10, no. 4, 2022, 647
Ling Zhu, “Sharp refined quadratic estimations of Shafer's inequalities”, AIMS Mathematics, 6, no. 5, 2021, 5020
Zhen-Hang Yang, Yu-Ming Chu, Xiao-Hui Zhang, “Sharp Cusa type inequalities with two parameters and their applications”, Applied Mathematics and Computation, 268, 2015, 1177
Xiao-Diao Chen, Song Jin, Chen Li-Geng, Yigang Wang, “A New Method for Refining the Shafer’s Equality and Bounding the Definite Integrals”, Results Math, 73, no. 2, 2018, 78
Bojan Banjac, Branko Malesevic, Milos Micovic, Bojana Mihailovic, Milica Savatovic, “The best possible constants approach for Wilker-Cusa-Huygens inequalities via stratification”, Appl Anal Discrete Math, 18, no. 1, 2024, 244