https://etd.repository.ugm.ac.id/penelitian/detail/1340522003never1.0https://etd.repository.ugm.ac.id/penelitian/detail/1361872003never1.0https://etd.repository.ugm.ac.id/penelitian/detail/1388772003never1.0https://etd.repository.ugm.ac.id/penelitian/detail/1388892003never1.0https://etd.repository.ugm.ac.id/penelitian/detail/1398632003never1.0https://etd.repository.ugm.ac.id/penelitian/detail/1429032003never1.0