Luyen, D.T. and Trang, M.T.T. 2023. Multiple solutions to boundary-value problems for fourth-order elliptic equations. Ukrains’kyi Matematychnyi Zhurnal. 75, 6 (Jun. 2023), 830 - 841. DOI:https://doi.org/10.37863/umzh.v75i6.6958.