1. Agmon, S.: Lectures on elliptic boundary value problems. Prepared for publication by B. Frank Jones, Jr. with the assistance of George W. Batten, Jr. Van Nostrand Mathematical Studies, No. 2. D. Van Nostrand Co., Inc., Princeton (1965)
2. Anupam, P.C., Horst, H.: Stability of the inverse boundary value problem for the biharmonic operator: logarithmic estimates. J. Inverse Ill-Posed Probl. 25(2), 251–263 (2017)
3. Ashbaugh, M.S.: On universal inequalities for the low eigenvalues of the buckling problem. In Partial Differential Equations and Inverse Problems. Contemp. Math., vol. 362, pp. 13–31. Am. Math. Soc., Providence, RI (2004)
4. Assylbekov, Y.M., Iyer, K.: Determining rough first order perturbations of the polyharmonic operator. (2017)
arXiv:1703.02569
5. Assylbekov, Y.M.: Inverse problems for the perturbed polyharmonic operator with coefficients in Sobolev spaces with non-positive order. Inverse Probl. 32(10), 105009 (2016)