Forbes e SiteCore
http://www.forbes.com/forbesinsights/sitecore/index.html
http://images.forbes.com/forbesinsights/StudyPDFs/Sitecore-Customers_for_Life-REPORT.pdf

KissMetrics/econsultancy.com
https://econsultancy.com/blog/63321-companies-more-focused-on-acquisition-than-retention-stats#i.la7l7lwsgejrxh

https://www.linkedin.com/pulse/article/20130604134550-284615-15-statistics-that-should-change-the-business-world-but-haven-t
https://www.linkedin.com/pulse/article/20140413033120-29200492-customer-acquisition-vs-customer-retention