MacDonald E, Steens A, Stene-Johansen K, Gillesberg Lassen S, Midgley Se, Lawrence J, Crofts J, Ngui S L, Balogun K, Frank C, Faber M, Gertler M, Verhoef L, Koopmans M, Sane J, van Pelt W, Sundqvist L, Vold L
Norwegian Institute of Public Health, Oslo, Norway.
Euro Surveill. 2013 Apr 25;18(17):20468.