1. [1] W. Berlin Science Center, “Do Travel Restrictions Work Against COVID-19 (Online source).” https://healthmanagement.org/c/hospital/news/do-travel-restrictions-work-against-covid-19.
2. [2] L. Kanagawa Chuo Kotsu Co., “Coronavirus Infection Prevention Strategies (Online source).” https://www.kanachu.co.jp/dia/news/detail?tbl=4&tid=70.
3. [3] Y. News, “Infected person gets on the bus, female driver positively `I think I took all possible measures (Online source).” https://www.yomiuri.co.jp/national/20200818-OYT1T50074.
4. [4] S. Bus and NAVITIME, “Support for Displaying Real-time Bus Crwodedness Levels.” https://www.seibubus.co.jp/news/uploads/bada778f26e2075dbc54dbb5cc116f05eb43cac7.pdf.
5. [5] Y. Furuya, H. Asahina, M. Yoshida, and I. Sasase, “Indoor crowd estimation scheme using the number of wi-fi probe requests under mac address randomization,” IEICE Trans. Inf. & Syst., vol.E104.D, no.9, pp.1420-1426, 2021. 10.1587/transinf.2020edp7228