A note on the paper "An inverse problem on determining second order symmetric tensor for perturbed biharmonic operator"

This note aim to provide a deeper insight on article dealing with an inverse problem for biharmonic operator with second order perturbation. More precisely, we are referring to the paper An inverse problem on determining second order symmetric tensor for perturbed biharmonic operator by Bhattacharyya and Ghosh An inverse problem on determining second order symmetric tensor for perturbed biharmonic operator, Math Ann (2021). Unfortunately, the paper contains some incorrect part. Indeed, a gap in the proof of the crucial proposition appears, whereas Proposition 3.6 in Bhattacharyya and Ghosh (Math Ann, 2021) is true only in a very specific case.