Twitchell, K.S.
Saudi Arabia : with an account of the development of its natural resources
Princeton University, 1958
Buku Teks SO
Twitcheil, K.S.
Saudi Arabia with an account of the development of its natural resources with the collaboration of and
New Jersey Princeton Univ. 1958
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Mining : Natural Resources Development
Artikel Jurnal
Natural resources and international development
edited by Marion Clawson
John Hopkins Press, 1965
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Natural resources and development
Federal Republic of Germany, 1977
Buku Teks SO