Jung, Hyejung; Kim, Jongbo; Lee, Seungju; Lee, Jinho; Kim, Jooyoun; Tsai, Perngjy; Yoon, Chungsik. Comparison of Filtration Efficiency and Pressure Drop in Anti-Yellow Sand Masks, Quarantine Masks, Medical Masks, General Masks, and Handkerchiefs. Aerosol and Air Quality Research. 2014, 14 (3): 991–1002. doi:10.4209/aaqr.2013.06.0201.