VOLUME 20 (1)/February 1990

Geological Institute, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria

Geological Institute, Bulgarian Academy of Sciences, 1113 Sofia
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Geological Institute, Bulgarian Academy of Sciences, 1113 Sofia
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Geological Institute, Bulgarian Academy of Sciences, 1113 Sofia

Geological Institute, Bulgarian Academy of Sciences, 1113 Sofia
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General Company for Hydraulic Studies, Horns, P. O. Box 752, Syria