https://etd.repository.ugm.ac.id/penelitian/detail/501702011never1.0https://etd.repository.ugm.ac.id/penelitian/detail/508872011never1.0https://etd.repository.ugm.ac.id/penelitian/detail/512272011never1.0https://etd.repository.ugm.ac.id/penelitian/detail/522672011never1.0https://etd.repository.ugm.ac.id/penelitian/detail/523582011never1.0https://etd.repository.ugm.ac.id/penelitian/detail/540042011never1.0