Line length revisited: following the research
Recent eye movement research is reviewed which questions whether long line lengths do cause reading difficulties.
Limiting content width (Wikimedia)
What is the CSS ‘ch’ Unit?
Line Lengths and CSS Length Units
Satzbreiten und Zeilenlängen im Schriftsatz
Zeilenlänge (Satzbreite)
How to Tune Typography Based on Characters Per Line
Readability: the Optimal Line Length