NEUTRINO MASS FROM THE BETA-SPECTRUM IN THE DECAY OF TRITIUM - BORIS, S; GOLUTVIN, A; LAPTIN, L; LUBIMOV, V; NAGOVIZIN, V; NOZIK, V; NOVIKOV, E; SOLOSHENKO, V; TIHOMIROV, I; TRETJAKOV, E; MYASOEDOV, N (PHYSICAL REVIEW LETTERS, 1987)