København, Ejnar Kunksgaard, 1955. 8vo. In the original printed wrappers. Offprint from ""Det Kongelige Danske Videnskabernes Selskab"", Matematisk-fysiske meddelelser, bind 29, no. 15. Very fine and clean. 60 pp.
Offprint of Kofoed-hansen and Nielsen's paper on how to construc a neutrino recoil spectrometer.