1. Aronszajn, N.: A unique continuation theorem for solutions of elliptic partial differential equations or inequalities of second order. J. Math. Pures Appl. 9(36), 235–249 (1957)
2. Baird, P., Eells, J.: A conservation law for harmonic maps. In: Geometry Symposium, Utrecht 1980 (Utrecht, 1980), volume 894 of Lecture Notes in Math., pp 1–25. Springer, Berlin (1981)
3. Baird, P., Kamissoko, D.: On constructing biharmonic maps and metrics. Ann. Global Anal. Geom. 23(1), 65–75 (2003)
4. Branding, V.: On conservation laws for the supersymmetric sigma model. Results Math. 72(4), 2181–2201 (2017)
5. Branding, V.: A Liouville-type theorem for biharmonic maps between complete Riemannian manifolds with small energies. Arch. Math. (Basel) 111(3), 329–336 (2018)