[en] The monocrystals of the cubic Laves phases Se-Al₂ have been produced for special measurements. Low-temperature anomalies were measured which were influenced by doping with foreign atoms. These anomalies, also called Kondo effect, were detected in some physical quantities like electric resistance, magnetic resistance, susceptibility, magnetization, specific heat, thermal conductivity and thermoelectric force. For diffuse magnetic neutron scattering, monocrystals with the dimensions 10 mm diameter and 70 mm length were produced. The materials used were La Al₂, (La Ce) Al₂, Ce Al₂, Y Al₂, and (Y Ce) Al₂. The monocrystals had to have an exactly cylindrical cross-section which was obtained by stripping by means of spark erosion machines. The measurements were carried out at the reactor of the Laue-Langevin Institute at Grenoble. In the experiments the magnetic behavior was measured by neutron scattering on monocrystals in the temperature range from 2.5 K to 300 K, the energy spectra having been registered. (orig.)