If you want to send a link to a user that will automatically open a specific article, first find that article in your articles list.

Beside the article, hover the quick menu, and select "share"

Accessing the quick menu

You'll be shown a drawer that will contain instructions on how to generate a direct link to that a page which when opened will auto open the chosen article.

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You can also access this when editing an article, by clicking on "Share" in the right column