抄録
Recently, international activities have been developed in order to establish the international temperature scale (IPTS) in the region below 13.81K, i.e., the downward extension of fhe IPTS. This article gives a short survey of these efforts; -Main points of arguements at the Comité Consultatif de Thermométrie and its Working Groups, the present state of our knowledge of thermodynamic temperatures in the region under investigation, and survey of practical thermometers as candidates for the standard thermometer.
