https://etd.repository.ugm.ac.id/penelitian/detail/1344512000never1.0https://etd.repository.ugm.ac.id/penelitian/detail/1412272000never1.0https://etd.repository.ugm.ac.id/penelitian/detail/1427632000never1.0https://etd.repository.ugm.ac.id/penelitian/detail/1428772000never1.0https://etd.repository.ugm.ac.id/penelitian/detail/1443102000never1.0