共 21 条
[1]
ABRAHAM S, 1983, PHS381680 US DHEW 11
[2]
BAIRD D, 1977, EPIDEMIOLOGY PREMATU, P5
[3]
DIXON WJ, 1981, BMDP STATISTICAL SOF
[4]
FREEMAN MG, 1970, PEDIATRICS, V46, P9
[7]
HACKMAN, 1983, J AM MED ASSOC, V250, P2016
[8]
HARDY JB, 1977, EPIDEMIOLOGY PREMATU, P105
[9]
Helwig J.T., 1979, SAS USERS GUIDE