UPPER LIMITS FOR THE DECAY OF TAU-LEPTONS INTO ETA-MESONS - ALBRECHT,H; BOCKMANN,P; GLASER,R; HARDER,G; KRUGER,A; NIPPE,A; REIDENBACH,M; SCHAFER,M; SCHMIDTPARZEFALL,W; SCHRODER,H; SCHULZ,HD; SEFKOW,F; et al. (ZEITSCHRIFT FUR PHYSIK C-PARTICLES AND FIELDS, 1988)