Dehm, G., Rühle, M., Ding, G., & Raj, R. (1995). Growth and Structure of Copper Thin Films Deposited on (0001) Sapphire by Molecular Beam Epitaxy. Philosophical Magazine B-Physics of Condensed Matter Statistical Mechanics Electronic Optical and Magnetic Properties, 71(6), 1111-1124. doi:10.1080/01418639508241899.