. 2016 Oct 3;6(4):533–545. doi: 10.1007/s13142-016-0438-0
© The Author(s) 2016
Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.
Fig. 1.
Registration and subsequent logins. CPD cigarettes per day