共 5 条
[1]
GORT M, DIVERSIFICATION INTE, P8
[2]
KRAMER LM, 1958, PUBLIC HLTH REPO OCT, P932
[3]
MANSFIELD E, EXPENDITURES FIRM RE, P4
[4]
*NAT AC SCI, IND RES LAB US
[5]
TOBIN J, 1958, ECONOMETRICA JAN, P24