TY  - BOOK
AU  - Campbell, Donald T,
AU  - Stanely, Julian C.
ED  - -.
TI  - Experimental and quasi-experimental designs for research: - 
T2  - -
SN  - - :
PY  - 1969///
CY  - Chiacago
PB  - Rand McNally & Co
KW  - research
KW  - -
N1  - -; Includes index and bib refs
N2  - -
ER  -