Kuwert E, Mondino A, Schygulla J. Existence of immersed spheres minimizing curvature functionals in compact 3-manifolds. Mathematische Annalen [Internet]. 2014  ;359:379?425. Available from: https://doi.org/10.1007/s00208-013-1005-3

Mondino A, Schygulla J. Existence of immersed spheres minimizing curvature functionals in non-compact 3-manifolds. Annales de l'Institut Henri Poincare (C) Non Linear Analysis [Internet]. 2014  ;31:707 - 724. Available from: http://www.sciencedirect.com/science/article/pii/S0294144913000851