Kraus, M. Numerical Methods in Plasma Physics (NMPP), Max Planck Institute for Plasma Physics, Max Planck Society;
https://publications.mfo.de/handle/mfo/3860 (Any fulltext)
Kraus, M. (2021). Geometric Integration of Degenerate Lagrangian Systems. In Geometric Numerical Integration (pp. 25-28). doi:10.4171/OWR/2021/17.