https://www.simplify3d.com/support/print-quality-troubleshooting/ (https://www.simplify3d.com/support/print-quality-troubleshooting/)
http://reprap.org/wiki/Print_Troubleshooting_Pictorial_Guide (http://reprap.org/wiki/Print_Troubleshooting_Pictorial_Guide)
http://support.3dverkstan.se/article/23-a-visual-ultimaker-troubleshooting-guide (http://support.3dverkstan.se/article/23-a-visual-ultimaker-troubleshooting-guide)