This is a test of the ESV CrossReference Tool. You can see how it handles each of these type of text references.

• Mark 6.34 (using period separator)
• Mark 6:34 (using colon separator)
• Mk 6:34 (using abbreviation)
• John 3:16-17 (using multiple verses)
• John 1:1, 14; 2:1 (complex listing)

Here is what the popup looks like:

• Clicking on the icon in the upper left brings you to the ESV.org site where you can click through to read the ESV Bible online.
• The speaker icon in the upper right will read the text out loud
• Social media links in the lower left
• "Learn more" brings you to info about the ESV CrossReference Tool.

Compare this to:

• Faithlife Reftagger
• NETBible Tagger