Cauchemez, S., Ferguson, N. M., Wachtel, C., Tegnell, A., Saour, G., Duncan, B., & Nicoll, A. (2009). Closure of schools during an influenza pandemic. The Lancet Infectious Diseases, 9, 473-481. https://doi.org/10.1016/s1473-3099(09)70176-8