1. International Tourist Numbers Could Fall 608–0% in 2020, Unwto Reports
https://www.unwto.org/news/covid-19-international-tourist-numbers-could-fall-60-80-in-2020
2. Visitor Arrivals to Hong Kong in July 2020
https://partnernet.hktb.com/en/research_statistics/latest_statistics/index.html
3. Baltics Open Europe’s First Pandemic ‘Travel Bubble’ as Curbs Ease
https://www.reuters.com/article/us-health-coronavirus-baltic/baltics-open-europes-first-pandemic-travel-bubble-as-curbs-ease-idUSKBN22Q3KM
4. Travel Bubbles: Commerce Minister Sounds Cautious Note on Hongkongers’ Holiday Plans. SCMP
https://www.scmp.com/news/hong-kong/hong-kong-economy/article/3091886/cloud-over-hongkongers-summer-holiday-plans-abroad
5. Five Things to Know About Travel Bubbles
https://www.smithsonianmag.com/travel/five-things-know-about-travel-bubbles-180974983/