1. Europe Energy Information Administration
https://ec.europa.eu/energy/home_en
2. Hydromagnetic equilibria and force-free fields
3. On magnetohydrodynamical equilibrium configurations;Shafranov;Sov. Phys. JETP,1958
4. Wangerin Functions;Aikawa,1975
5. The Vacuum Poloidal Flux Functions Satisfying of the Grad–Shafranov Equation in the Flat-Ring Cyclide Coordinate System;Honma;Hokkaido Daigaku Kogakubu Kenkyu Hokoku,1979