[1] https://googleblog.blogspot.ca/2009/06/lets-make-web-faster.html
[2] BONDI, André B. Foundations of Software and System Performance Engineering: Process, Performance Modeling, Requirements, Testing, Scalability, and Practice. Upper Saddle River, NJ: Addison-Wesley, 2015.
[3] MEIER, J. D. et al. Performance Testing Guidance for Web Applications. Redmond, WA: Microsoft Corporation, 2007.
[4] https://www.smashingmagazine.com/2015/11/why-performance-matters-part-2-perception-management/