@unpublished{repository43139,
           title = {Perangkat Pembelajaran problematika 7C},
       publisher = {Universitas Muhammadiyah Prof DR Hamka},
            note = {Unpublished},
          author = {Wahidin, Wahidin},
             url = {http://repository.uhamka.ac.id/id/eprint/43139/}
}