Nicolai, Hermann Quantum Gravity & Unified Theories, AEI-Golm, MPI for Gravitational Physics, Max Planck Society;
351293.pdf (Publisher version), 316KB
Hoppe, J., & Nicolai, H. (1987). Relativistic minimal surfaces. Physics Letters B, 196(4), 451-455. doi:10.1016/0370-2693(87)90800-8.