共 4 条
[1]
BARNETT AJG, 1950, J AGR SCI, V40, P50, DOI 10.1017/S0021859600045494
[2]
DIJKSTRA ND, 1949, VERSL LANDBOUWK ONDE, P10
[3]
WATSON SJ, 1939, SCI PRACTICE CONSERV, P508
[4]
WEDEMEYER K, 1899, LANDW VERSSTA, V51, P375