Bairfelt, S. and Wilkinson, T. (2015) Secondary (desk) research from Purple Market Research. Purple Market Research [online].

Cleverism (2015) How to perform an insightful secondary market research. Marketing 101 [online, 13 May].

Ridley, D. (2012) The Literature Review: A Step-by-Step Guide for Students (2nd edition). London: Sage.

Wallace, M. and Wray, A. (2011) Critical Reading and Writing for Postgraduates (2nd edition). London: Sage.