| article html file updated | 7 February 2020 06:17 CET | Update | https://www.mdpi.com/2077-0375/6/2/21 |
| article html file updated | 5 May 2019 20:39 CEST | Update | N/A |
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| article html file updated | 4 July 2016 05:05 CEST | Original file | N/A |
| article xml uploaded. | 23 March 2016 10:53 CET | Original file | https://www.mdpi.com/2077-0375/6/2/21/xml |
| article pdf uploaded. | 23 March 2016 10:53 CET | Version of Record | https://www.mdpi.com/2077-0375/6/2/21/pdf |
