1. Measuring mobile phone use: Gender, age and real usage level in relation to the accuracy and validity of self-reported mobile phone use
2. Measuring Mobile Phone Use: Self-Report Versus Log Data
3. Chavin, J., Ginwala, A., & Spear, M. (2012). The future of mobile messaging: Over-the-top competitors threaten SMS. McKinsey & Company Telecom, Media & High Tech Extranet. Retrieved from https://https://tmt.mckinsey.com/content/industry/Consumer
4. Church, K., & de Oliveira, R. (2013). What’s up with WhatsApp? Comparing mobile instant messaging behaviors with traditional SMS. Proceedings of the 15th International Conference on Human-Computer Interaction with Mobile Devices and Services, Mobile HCI 2013. Munich: Institut für Informatik. Retrieved from http://www.ic.unicamp.br/~oliveira/doc/MHCI2013_Whats-up-with-whatsapp.pdf
5. Deloitte. (2014). Short messaging services versus instant messaging: Value versus volume. Retrieved from http://www2.deloitte.com/content/dam/Deloitte/global/Docu ments/Technology-Media-Telecommunications/gx-tmt-2014prediction-short-messaging -services.pdf