Bài báo khoa học

1916, Piper Charles V.

1951, Burton, Glennw

1985, Bryan, Frank L

1994, Eele, Graham

1994, Andersen, Per Pinstrup

1996, Maxwell, Simon

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1997, Karlen, D. L., Mausbach, M.J., Doran, J.W., Cline, R.G., Harris, R.F., Schuman, G.E.

1917, Fippin Elmer O.

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1918, Skinner J. J.

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1994, Campbell Platt, Geoffrey

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