Read this chapter: Where can you find secondary data sources?

Riedel, M. (2000). Sources of secondary data. In Research strategies for secondary data: a perspective for criminology and criminal justice (pp. 27-48). Thousand Oaks, CA: SAGE Publications, Inc.

Read this chapter: How can you assess the credibility and relevance of secondary data sources?

Secondary data and research. (2014). In Clow, K. E., & James, K. E. Essentials of marketing research: Putting research into practice (pp. 62-94). London: SAGE Publications Ltd