| article html file updated | 6 February 2020 08:11 CET | Update | https://www.mdpi.com/2223-7747/3/2/209 |
| article html file updated | 7 May 2019 16:47 CEST | Update | - |
| article html file updated | 21 March 2019 14:32 CET | Update | - |
| article html file updated | 20 August 2015 01:06 CEST | Original file | - |
| article pdf uploaded. | 26 March 2014 09:25 CET | Version of Record | https://www.mdpi.com/2223-7747/3/2/209/pdf |
