1. 2B. V. DuttandF, and A. Kroeger , "High-Temperature Defect Structure of iron-Doped alpha-AIumina ,"ibid., [11 -12 ] 11 -12 .
2. 4S. K. Mohapatra, and F. A. Kroeger , "The Defect Structure of alpha- Al2O3Doped with Titanium ," ibid., [9 -10 ] 9 -10 .