- Correspondence to Joachim Heinrich, Institute of Epidemiology I, Helmholtz Zentrum München, German Research Centre for Environmental Health, Ingolstädter Landstr. 1, Neuherberg 85764, Germany;
- Received January 23, 2014
- Revised April 23, 2014
- Accepted May 9, 2014
- First published May 26, 2014.
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