%0 Journal Article %A Poerschke, R. %A Wollenberger, H. %T A helium-cooled magnetic amplifier for d c measurements in the picovolt range %J Cryogenics : low temperature engineering, applied super conductivity, cryoelectronics, cryophysics %V 10 %N 4 %@ 0011-2275 %C Amsterdam %I Elsevier %M RWTH-CONV-011168 %P 333-335 %D 1970 %F PUB:(DE-HGF)16 %9 Journal Article %U <Go to ISI:>//WOS:A1970G901400015 %R 10.1016/0011-2275(70)90067-6 %U https://publications.rwth-aachen.de/record/129994