1. ISO 9000:2005, Quality Management Systems – Fundamentals and Vocabulary (International Organization for Standardization (ISO), Geneva, 2005)
2. ISO 8402:1994, Quality Management and Quality Assurance – Vocabulary (International Organization for Standardization (ISO), Geneva, 1994)
3. ITU-T Recommendation P.10/G.100, Vocabulary for Performance, Quality of Service and Quality of Experience (International Telecommunication Union (ITU), Geneva, 2017)
4. M. Varela, L. Skorin-Kapov, T. Ebrahimi, Quality of service versus quality of experience, in Quality of Experience, ed. by S. Möller, A. Raake (Springer, Cham, 2014), pp. 85–96
5. A. Raake, Speech Quality of VoIP: Assessment and Prediction (John Wiley & Sons, Ltd, Chichester, 2006)