TY  - BOOK
AU  - Creswell. J.W.
TI  - Research design: qualitative, quantitative, and mixed methods approaches
SN  - 9781412965569
AV  - DUCE H62.C6963 
PY  - 2009///
CY  - London
PB  - SAGE
N1  - includes an index  and references
ER  -