Bound state properties, positron annihilation and hyperfine structure splittings in the four-body positron-helium 
He(
)] and 
He()] ions
Eur. Phys. J. D, 79 4 (2025) 38
Published online: 24 April 2025
DOI: 10.1140/epjd/s10053-025-00990-3