2. Cohen, Manion & Morrison (2000): “A systematic process of enquiry with a view to providing information as a basis for conclusion”
3. Kerlinger & Lee (2000): “Systematic, controlled, empirical and critical investigation of hypothetical propositions about the presumed relations among natural phenomena”
4. Meleong (2004): “A systematic, controlled, empirical, and critical investigation of a hypothetical proposition for the purpose of establishing or confirming new knowledge”
5. Punch (2005): “Scientific investigation using structured methods which aim at the collection of empirical data and the discovery of generalizations about populations or processes”
6. Babbie (2007): “An attempt to gather information about a particular topic with the intention of drawing some conclusions about that topic”
7. Creswell (2012): “A process of systematic inquiry which entails the collection and analysis of data for the purpose of answering a research question”