1. Asthma caused by occupational exposures is common – A systematic analysis of estimates of the population-attributable fraction
2. Defining and investigating occupational asthma: a consensus approach
3. Nicholson PJ Cullinan P Burge PS Boyle C .Occupational asthma: prevention, identification & management: systematic review & recommendations 2010 London British Occupational Health Research Foundation
4. Scottish Intercollegiate Guidelines Network (2000) SIGN 50: a guideline developer's handbook (SIGN, Edinburgh).
5. The AGREE Collaboration (2001) Appraisal of Guidelines for Research and Evaluation (AGREE) Instrument. (The AGREE Collaboration, London) www.agreecollaboration.org [Accessed 25 January 2012].