RANI, Anu and GOYAL, Sarika. Multiple solutions for biharmonic critical Choquard equation involving sign-changing weight functions. Topological Methods in Nonlinear Analysis. Online. 6 March 2022. Vol. 59, no. 1, pp. 221 - 260. [Accessed 22 July 2024]. DOI 10.12775/TMNA.2021.025.