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Aufschluß von Steinkohlenlagerstätten in Entwicklungsländern
Stolte, Gerd, (1987)
Steam coal: a partial survey
Banks, Ferdinand E., (1987)
Present and future coal trade patterns (with particular emphasis on developing countries)
Alkema, H. J., (1983)
Linking Poverty Reduction and Environmental Management Policy Challenges and Opportunities
(2002)
Quarterly external debt statistics / Special data dissemination system
Quarterly public sector debt