If you stumble across a hyperlink that no longer resolves to a web resource, please let us know by raising a support ticket!
Unfortunately maintaining active hyperlinks to external resources for further reading is hard. These web pages can be removed, or have their URLs changed so they no longer direct you to the right resource.
We'll attempt to find where the resource was moved to, replace it with a similar resource, or remove the reference from the course material to prevent others from experiencing this issue.