References
PERSONAL COMMUNICATION.MINING MAGAZINE, P. 151 (AUG. 1984).INTERNATIONAL MINING, P. 13 (OCT. 1984).SKILLINGS' MINING REVIEW, P. 4 (JAN. 1987).INTERNATIONAL MINING, P. 15 (NOV. 1987).MINING JOURNAL, P. 334 (OCT. 28, 1988).SKILLINGS' MINING REVIEW, P. 4 (NOV. 26, 1988).ENGINEERING AND MINING JOURNAL, P. 22 (FEB. 1989).SKILLINGS' MINING REVIEW, P. 7 (MAR. 25, 1989).WORLD MINING EQUIPMENT, P. 52 (MAY 1989).INTERNATIONAL MINING, P. 11 (MAY 1989).MINING JOURNAL, P. 390 (MAY 19, 1989).RTZ CORP., LETTER FROM P.C.F. CROWSON (JUNE 16, 1989).METAL BULLETIN MONTHLY, P. 6 (AUG. 1989).ENGINEERING AND MINING JOURNAL, P. 48 (AUG. 1989).MINING MAGAZINE, P. 184 (SEPT. 1989).METALS WEEK, PP. 1, 2 (MAY 21, 1990).DEPARTMENT OF STATE TELEGRAM (OCT. 1990).SOMINCOR, P. 14 (MAR. 1989).SOMINCOR, P. 12 (1991 ANNUAL REPORT).SOMINCOR, P. 14 (1992 ANNUAL REPORT).METALS WEEK, P. 2 (FEB. 15, 1993).LECA, XAVIER, LA DECOUVERTE DES AMAS SULFURES CACHES DENEVES-CORVO (SUD DU PORTUGAL). ESSAI DE METHODOLOGIE,CHRON. RECH. MIN., NO. 479, 1985, P.51-62.ALBOUY, L., L.N. CONDE, F. FOGLIERINI, X. LECA, A. MORIKIS,LE GISEMENT DE SULFURES MASSIFS POLYMETALLIQUES DE NEVES-CORVO (BAIXO ALENTEJO, SUD PORTUGAL), CHRONIQUE DE LARECHERCHE MINIERE, NO. 460, 1981, P.5-27.MINING WORLD, P. 12 (MAY 21, 1990).METAL BULLETIN, P. 12 (FEB. 18, 1993).METAL BULLETIN MONTHLY, SOMINCOR'S NEVES-CORVO GETSUNDERWAY, AUG. 1989 P. 6-9BROOK HUNT & ASSOCIATES LIMITED, EUROPEAN & AFRICANCOPPER MINES COST STUDY (1988-1995), VOL. 3, P. 162 (1992)RTZ CORP., 1993 20F, P.12.RTZ CORP., 1994 20-F, P.13,14.