共 9 条
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- [4] Jackson M L, 1958, SOIL CHEMICAL ANALYS, P187
- [5] MCMURDO GA, 1916, USDA402 B
- [6] OLSEN SR, 1954, USDA939 CIRC
- [7] OLSON HM, 1960, ND FARM RES, V21
- [8] POST AH, 1966, 609 MONT AGR EXP STN
- [9] ROBERTSON DW, 1942, 472 COL EXP STN B