https://etd.repository.ugm.ac.id/penelitian/detail/503072011never1.0https://etd.repository.ugm.ac.id/penelitian/detail/503612011never1.0https://etd.repository.ugm.ac.id/penelitian/detail/504222011never1.0https://etd.repository.ugm.ac.id/penelitian/detail/508302011never1.0https://etd.repository.ugm.ac.id/penelitian/detail/513142011never1.0https://etd.repository.ugm.ac.id/penelitian/detail/514572011never1.0https://etd.repository.ugm.ac.id/penelitian/detail/517632011never1.0https://etd.repository.ugm.ac.id/penelitian/detail/518512011never1.0