https://etd.repository.ugm.ac.id/penelitian/detail/192272002never1.0https://etd.repository.ugm.ac.id/penelitian/detail/194022002never1.0https://etd.repository.ugm.ac.id/penelitian/detail/206192002never1.0https://etd.repository.ugm.ac.id/penelitian/detail/206202002never1.0