??13C VALUES OF ORGANIC CONSTITUENTS AND POSSIBLE SOURCE OF HUMIC SUBSTANCES IN JAPANESE VOLCANIC ASH SOILS
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1989 ◽
Vol 35
(2)
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pp. 257-270
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2004 ◽
Vol 68
(1)
◽
pp. 313
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2001 ◽
Vol 47
(2)
◽
pp. 411-418
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