Unknown Author
Li, Jichun (Petroleum engineer)
N. S. Pechuro
N. Pechuro
United Nations. Economic Commission for Europe
J. G. Kirby
C. Hennig
C. Henning
A. Kim
F. S. Lott
Conoco Coal Development Company. Research Division
Paul D. Krauss
Jack Miller Reid
Xionglin Luo