TY  - BOOK
AU  - Cook, Thomas D.
AU  - Campbell, Donald T.
TI  - Quasi-experimentation : 
SN  - 0395307902
U1  - 519.5  1
PY  - 1979///
CY  - Boston
PB  - Houghton mifflin Company
KW  - Validity
KW  - Inferring cause from passive observation
KW  - The conduct of randomized experiments
ER  -