https://etd.repository.ugm.ac.id/penelitian/detail/1601342018never1.0https://etd.repository.ugm.ac.id/penelitian/detail/1632612018never1.0https://etd.repository.ugm.ac.id/penelitian/detail/1632672018never1.0https://etd.repository.ugm.ac.id/penelitian/detail/1632782018never1.0https://etd.repository.ugm.ac.id/penelitian/detail/1652702018never1.0https://etd.repository.ugm.ac.id/penelitian/detail/1652712018never1.0