Gripenet: an internet-based system to monitor influenza-like illness uniformly across Europe
van Noort, S P and Muehlen, M and Rebelo de Andrade, H and Koppeschaar, C and Lima Lourenço, J M and Gomes, M GM, Eurosurveillance, 12, 722 (2007), https://doi.org/10.2807/esm.12.07.00722-en