https://etd.repository.ugm.ac.id/penelitian/detail/560312012never1.0https://etd.repository.ugm.ac.id/penelitian/detail/560322012never1.0https://etd.repository.ugm.ac.id/penelitian/detail/569622012never1.0https://etd.repository.ugm.ac.id/penelitian/detail/569692012never1.0https://etd.repository.ugm.ac.id/penelitian/detail/572522012never1.0https://etd.repository.ugm.ac.id/penelitian/detail/584022012never1.0https://etd.repository.ugm.ac.id/penelitian/detail/584682012never1.0https://etd.repository.ugm.ac.id/penelitian/detail/584702012never1.0