[en] It often occurs that, in a rare-earth compound having a singlet electronic ground state, a long-range magnetically ordered state is formed by coupling of the nuclear spins with the electrons through the hyperfine interaction, at millikelvin temperatures. Neutron scattering has been used to measure the details of the magnetization processes of both the electrons and the nuclear spins in the coupled state in PrSn₃, HoVO₄, and PrCu₂. The polarized nuclear spins could be observed through spin dependent nuclear scattering by ¹⁴¹Pr and ¹⁶⁵Ho. The experimental results for PrSn₃ and HoVO₄ can be explained very well based on mean field considerations. For PrCu₂, a recent experiment indicates that a sinusoidal screw structure is realized simultaneously both in the electronic and nuclear spin systems of this material