Creswell, John W. (2014) (E-BOOK): RESEARCH DESIGN. SAGE Publications, Inc.. ISBN 978-1-4522-2610-1

Creswell, John W. (2013) (E-BOOK): QUALITATIVE INQUIRY RESEARCH DESIGN. 3 ed. SAGE Publications, Inc.. ISBN 978-1-4129-9530-6

Creswell, John W. (2009) (E-BOOK): RESEARCH DESIGN QUALITATIVE, QUANTITATIVE, AND MIXED METHODS APPROACHES. SAGE Publications, Inc.. ISBN 978-1-4129-6557-6