http://www.damtp.cam.ac.uk/user/as629/PartIIIL05/course_blogL05.html
Energy Principle Ref.
The original famous paper on the MHD energy principle is I. B. Bernstein, E. A. Frieman, M. D. Kruskal & R. M. Kulsrud, Proc. Roy. Soc. LondonA244, 17 (1958)
Lagrangian formulation of MHD and the action principle are discussed in the excellent original paper by Newcomb:
W. A. Newcomb, Nucl. Fusion: 1962 Supplement, Part 2, p. 451 (distributed in class)
A more recent useful reference is D. Pfirsch & R. N. Sudan, Phys. Fluids B 5, 2052 (1993)
