1. talk at the GUD Workshop;Rubbia,1981
2. H.H. Chen, Proc. 1982 Summer Workshop on Proton Decay Experiments, ANL-HEP-PR-82-24, p. 274
3. Science Underground;Chen,1982
4. Workshop on Low-Level Counting in Liquid Argon and Xenon Detectors and Telescopes;Aprile,1987