@unpublished{repository10451,
           title = {BAP, Daftar Hadir, DPNA, Mata kuliah Teori Belajar 2A},
            note = {Unpublished},
       publisher = {Universitas Muhammadiyah Prof. Dr. HAMKA},
             url = {http://repository.uhamka.ac.id/id/eprint/10451/},
          author = {make\_bibtex\_string expected hash reference}
}