Finding the date a page was created or updated

In the C.A.T. PAT, learners are meant to list the date of web pages or articles. What does one do when the date is nowhere to be found?

Here is a cool trick to find out the date when a document/page was created or modified.

[simultaneouslysarah]

Thanks so much! Bless Jesus for this video. This worked for me, I hope more people see this video and avoid( n.d) in their referencing.