How to cross-reference Snapnumbers™
 
METHOD 1:  REFERENCE TO NUMBERED ITEM

Put the cursor where the cross-reference belongs and click References, Cross-reference.  In the Cross-reference screen, choose Reference type = Numbered item, Insert reference to = Paragraph number, select the paragraph to which you are referring, and click Insert.

METHOD 2:  REFERENCE TO BOOKMARK

Step 1:  Create a bookmark in the paragraph to which you are referring.  It can appear anywhere in the paragraph but a best practice is to put it between the Snapnumber and the text, where it's unlikely to be accidentally deleted or moved.  Give it a name that identifies the content of the paragraph.  (To create a bookmark, position the cursor then click Insert, Bookmark, type the bookmark name, and click Add.)

 
Step 2:  Put the cursor where the cross-reference belongs and click References, Cross-reference.  In the Cross-reference screen, choose Reference type = Bookmark, Insert reference to = Paragraph number, select the bookmark to which you are referring, and click Insert.

COMPARISON OF METHOD 1 VERSUS METHOD 2

Method 1 is easier, and Method 2 is more stable. Method 1 sometimes breaks when paragraphs are cut-and-pasted, or scattered among various documents and then reassembled.  

Method 2 works even if the reference and the target paragraph are scattered in several documents, as long as they are eventually rejoined in a single document.  (This is handy if, for instance, you're using Doxserá's Folio feature to assemble finished documents from multiple sources.)  

So use Method 1 when working in an unremarkable, straightforward document, and Method 2 when working in a more sophisticated document that will be subject to a lot of revisions and rearrangements.