HEAVY FLAVOR PRODUCTION IN Z DECAYS - DECAMP,D; DESCHIZEAUX,B; GOY,C; LEES,JP; MINARD,MN; CRESPO,JM; DELFINO,M; FERNANDEZ,E; MATO,P; MIQUEL,R; MIR,LM; ORTEU,S; et al. (PHYSICS LETTERS B, 1990)