Long runs: Your essential guide to running far
A Beginner's Guide to the Long Run
Add a weekly medium-long run to boost endurance - Canadian Running Magazine
How to Prepare for a Long Distance Run, by OpenRace
Why you need to run long - Brooks Running AU Blog
Running How Often Should You Run?
Is your long run too long? - Canadian Running Magazine
Mo Farah vows that he will succeed in the long run
Long runs: Your essential guide to running far