'Did you have flu last week?’ A telephone survey to estimate a point prevalence of influenza in the Swedish population
Payne, L and Kühlmann-Berenzon, S and Ekdahl, K and Giesecke, J and Högberg, L and Penttinen, P, Eurosurveillance, 10, 585 (2005), https://doi.org/10.2807/esm.10.12.00585-en