In a business letter, 
what's the correct or more frequent way to write date ranges?


  from the 4th to the 8th of June 2014, we have been working on the
  project


or


  from 4 to 8 June 2014, we have been working on the project


or


  In June 2014, 4 to 8, we have been working on the project



Question: How do I copy some smart object layers to another file and keep them linked
Answer: In all versions prior to the Jan 2014 update to Photoshop CC that's just the way Smart Objects work, unfortunately.

Photoshop CC, as of Jan 2014, allows you to choose between embedding and linking when creating a Smart Object. Linked S.O.'s behave just like linked files in Illustrator or InDesign. If the external (linked) file is edited and saved, all the Photoshop documents it is linked to can update accordingly. This external link is maintained when S.O.'s are copied from one document to another, so this would give you the functionality you're looking for.

To link, rather than embed, an object as a Smart Object, either hold down Alt/Option while dragging it into Photoshop or use `File > Place Linked...".