1. [1] Brooks (R.), Perry (P.), Yang (P.).— Isospectral sets of conformally equivalent metrics. Duke Math. J. 58, no.1, p. 131-150 (1989).
2. [2] Chang (S.-Y. A.), Gursky (M.), Wolff (T).— Lack of compactness in conformal metrics with L d/2 curvature. J. Geom. Anal. 4, no.2, p. 143-153 (1994).
3. [3] Chang (S.-Y. A.), Yang (P. C.-P.).— Compactness of isospectral conformal metrics on S 3 . Comment. Math. Helv. 64, no.3, p. 363-374 (1989).
4. [4] Chang (S.-Y. A.), Yang (P. C.-P.).— Isospectral conformal metrics on 3-manifolds. J. Amer. Math. Soc. 3, no.1, p. 117-145 (1990).
5. [5] Colbois (B.), El Soufi (A.).— Extremal eigenvalues of the Laplacian in a conformal class of metrics: the ‘conformal spectrum’. Ann. Global Anal. Geom. 24, no.4 p. 337-349 (2003).