1. Cai, S., & Jun, M. (2003). Internet users' perceptions of online service quality: a comparison of online buyers and information searchers. Managing Service Quality, 13, 504-519.
2. Cai, S., Xu, Y., & Yang, X. (2019). Understanding the impact of service quality on online event satisfaction: The role of tangibility. International Journal of Information Management, 44, 30-41.
3. Cole, C. (2007). Consumer Behavior. Encylopedia of Gerontology.
4. Davenport. (2001). How Do They Know Their Customers So Well?
5. Garcia, N., Saura, I., & Orejuela, A. (2020). Purchase intention and purchase behavior online: A cross-cultural approach. Heliyon.
6. Kassim, N., & Abdullah, N. A. (2010). The effect of perceived service quality dimensions on customer satisfaction, trust, and loyalty in e‐commerce settings: A cross cultural analysis. Asia Pacific Journal of Marketing and Logistics, 22, 351-357.
7. Parasuraman, A., Zeithaml, V., & Berry, L. (1988). A Conceptual Model of Service Quality and Its Implications for Future Research. Journal of Marketing, 64,12-40.
8. Rice, M. (2022, Jun 28). builtin: Freemium, Explained. Retrieved from Freemium, Explained: https://builtin.com/product/freemium
9. Segal, T. (2022, December 26). Investopedia: Freemium: Definition, Examples, Pros & Cons for Business. Retrieved from Freemium: Definition, Examples, Pros & Cons for Business: https://www.investopedia.com/terms/f/freemium.asp
10. Vaz, A., & Mansori, S. (2013). Malaysian Private Education Quality: Application of SERVQUAL Model. International Education Studies, 6, 164-170.
11. Zeithaml, V., Berry, L., & Parasuraman, A. (1996). The Behavioral Consequences of Service Quality. Journal of Marketing, 60, 31-46.