Print Quality Troubleshooting Guide
https://www.simplify3d.com/support/print-quality-troubleshooting/
Troubleshooting Guide to 21 Common 3D Printing Problems
https://all3dp.com/common-3d-printing-problems-and-their-solutions/
The 'Art' of failure - When 3D prints go wrong and lessons from failure
http://richrap.blogspot.lu/2011/10/art-of-failure-when-3d-prints-go-wrong.html
Print Troubleshooting Pictorial Guide
http://reprap.org/wiki/Print_Troubleshooting_Pictorial_Guide
A visual Ultimaker troubleshooting guide
http://support.3dverkstan.se/article/23-a-visual-ultimaker-troubleshooting-guide