@unpublished{repository45749,
       publisher = {Universitas Muhammadiyah Prof. Dr. HAMKA},
            note = {Unpublished},
           title = {bukti ajar SI 4},
             url = {http://repository.uhamka.ac.id/id/eprint/45749/},
          author = {Hamid Al Jufri, Jufri}
}