Noether symmetries and isometries of the area-minimizing Lagrangian on vacuum classes of pp-wavesAkram Mohammadpouri, Mir Sajjad Hashemi and Sona SamaeiEur. Phys. J. Plus, 138 2 (2023) 112DOI: https://doi.org/10.1140/epjp/s13360-023-03693-z