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)