1. Hardy G H. Note on a theorem of Hilbert concerning series of positive terms. Proc Lond Math Soc (3), 1925, 23: 45--48.
2. He B, Hong Y, Li Z H. Conditions for the validity of a class of optimal Hilbert type multiple integral inequalities with nonhomogeneous kernels. J Inequal Appl, 2021, 2021: 64.
3. Hong Y. On the norm of a series operator with a symmetric and homogeneous kernel and its application (in Chinese). Acta Math Sinica (Chin Ser), 2008, 51: 365--370.
4. Hong Y. Structural characteristics and applications of Hilbert's type integral inequalities with homogeneous kernel (in Chinese). J Jilin Univ (Sci Ed), 2017, 55: 189--194.
5. Hong Y, Chen Q. Equivalence condition for the best matching parameters of multiple integral operator with generalized homogeneous kernel and applications (in Chinese). Sci Sin Math, 2023, 53: 717-728.