Sugihartono, Iwan, 		Budi, Esmar, AND 		Budi, Agus Setyo.
" X-ray Photoelectron Spectroscopy (XPS) Analysis of Undoped ZnO and ZnO:Er Thin Films" <em>Jurnal ILMU DASAR</em> [Online], Volume 16 Number 1 (11 June 2015)