Acta Cryst. (1991). A47, 655-685
BY SYDNEY R. HALL, Crystallography Centre, University of Western Australia, Nedlands 6009, Australia
FRANK H. ALLEN, Crystallographic Data Centre, University Chemical Laboratory, Lensfield Road, Cambridge CB2 1EW, England
AND I. DAVID BROWN, Institute for Materials Research, McMaster University, Hamilton, Ontario L8S 4M1, Canada
(Received 8 April 1991; accepted 28 June 1991)Copyright © 1991 International Union of Crystallography
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