I saw this sentence "He's a <a>big fan</a> of Elvis Presley" in Longman dictionary.<br/><a href='http://www.ldoceonline.com/dictionary/fan_1' target='_blank' rel='nofollow'>http://www.ldoceonline.com/dictionary/fan_1</a><br/><br/>but I also saw this sentence "He claims to have been a friend of Elvis Presley's" in a text book.<br/>Which is correct, Elvis Presley or Elvis Presley's?<br/>