A survey of COVID-19 contact-tracing apps. - Nasro Min-Allah; Bashayer Abdullah Alahmed; Elaf Mohammed Albreek; Lina Shabab Alghamdi; Doaa Abdullah Alawad; Abeer Salem Alharbi; Noor Al-Akkas; Dhiaa Musleh; Saleh Alrashed (Comput. Biol. Medicine, 2021)