Knowledge, practice, and barriers of optimal mask usage among general public – A cross-sectional study from Kerala, South India oleh Aditya Ashok, Akhilesh Kunoor, Midhun Rajeev, Soumya Melepurakkal, Aravind Mohankumar Syamala, Sarath Venugopal, Vishnu Gopalakrishnan, Tajik Muhammed Shafi