[Secular change of background activity in Ge(Li) detector (author's transl)].
D001417:Background Radiation; D005720:Gamma Rays; D005857:Germanium; D008094:Lithium; D011835:Radiation Protection; D011839:Radiation, Ionizing; D011874:Radiometry / Q000295:instrumentation
D005857:Germanium; D008094:Lithium