Notes in note?

First, have your note tool open to the note you already have on Gal 1:1.

Then open your other resource (ie. Halley's Bible Handbook) and select the appropriate text.  Then on the note you already created on Gal 1:1, you click "Add anchor", and it should have the radio button turned on for "Selected Text".  Then click "Done".  

Now when you pull up the note on Gal 1:1, you can click on the link under "Anchors" and jump to resource.

There may be other ways, but that is how I do this.

Bob

Graham's option is another good way.  Both ways have side effects.  Graham's links can be embedded into the note text.  My suggestion has the link as an anchor and not embedded in the text.  If you use the anchor approach, you have a note icon in Halley's Bible Handbook, so that later while reading Halley's you will come across an icon and you can then jump back to your note and see how it relates to Gal. 1:1.  

With the URL link approach, if you are reading Halley's, you will not have any indication that you previously made a link to some text in Halley's.

Just some things to consider, when deciding on an approach.

Bob