@unpublished{repository11992,
       publisher = {UHAMKA},
           title = {Peer Reviu\_Is exemplification the one and only way to describe that empty set is subset 
of any sets?},
            note = {Unpublished},
             url = {http://repository.uhamka.ac.id/id/eprint/11992/},
          author = {Samsul Maarif, SMF}
}