HultqvistB.: Studies on natural-occurring ionizing radiations with special reference to radiation doses in Swedish houses of various types. Kungl. Svenska Vetenskapsakademiens handlingar, 4e serien, band 6, nr 3, 1956.
2.
LindellB.ReizensteinP.: A Swedish building material for low-radioactivity laboratories. Arkiv Fysik26 (1963), 65.