Hi Fred, maybe you can find the answer in Creswell's books (http://www.mixedmethods.org/creswell.html)

Thank you Yansyah. This is very helpful.

Article Searching for Qualitatively Driven Mixed Methods Research: A...

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Article Mixing methods in a qualitatively driven way

this book should be read

Quivy, R. Van Campenhoudt, L. (1995), Manuel de recherche en sciences sociales, Paris: Dunod.

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For a constructivist approach, as a theoretical basis, ”The Social Construction of Reality”, by Peter L. Berger and Thomas Luckmann is a book that should not be missing.

Thanks Simona. It's helpful