@unpublished{repository11156,
           title = {Workshop Matematika 4A,4B,4D},
            note = {Unpublished},
       publisher = {Universitas Muhammadiyah Prof. DR. Hamka},
             url = {http://repository.uhamka.ac.id/id/eprint/11156/},
          author = {Slamet Soro, SS}
}