Covert observation in practice : lessons from the evaluation of the prohibition of smoking in public places in Scotland

Petticrew, M, Semple, S, Hilton, S, Creely, K S, Eadie, D, Ritchie, D, Ferrell, C, Christopher, Y & Hurley, F 2007, 'Covert observation in practice : lessons from the evaluation of the prohibition of smoking in public places in Scotland', BMC Public Health, vol. 7, 204. https://doi.org/10.1186/1471-2458-7-204