The possessive in English can take main 2 forms: Shakespeare's work (the work belonging/pertaining to Shakespeare) The work of Shakespeare (the work belonging/ pertaining to Shakespeare) These refer to all Shakespeare's work (plays, poetry) A work of Shakespeare (a piece of work - play, poetry belonging/ pertaining to Shakespeare) This refers to a specific example of part of his work. So some examples would be: Shakespeare's work is universally admired. The work of Shakespeare is universally admired. A work of Shakespeare which I greatly admire is "The Merchant of Venice". In spoken, very informal English among natives, you can hear expressions such as "She is a friend of my mum's" with an "s" pronounced at the end - but this is not really "correct" use of English :-)

Yes, you could say that and there would probably not be much difference between the two expressions in this case. But consider "a portrait of Shakespeare" -- a portrait depicting him -- and "a portrait of Shakespeare's" -- a portrait belonging to him, possibly depicting someone else.