1. The effect of orientation on Knoop hardness of single crystals of zinc and silicon ferrite;Daniel;Trans. Am. Soc. Met.,1949
2. A stereographic representation of Knoop hardness anisotropy;Garfinkle;Trans. Metall. Soc. AIME,1968
3. Anisotropy in the hardness of single crystals;Brookes,1971
4. Microhardness anisotropy of silicon carbide;Sawyer;J. Mater. Sci.,1980
5. Microhardness anisotropy of SrF2, CaF2, NaCl and AgCl crystals;Chin;J. Mater. Sci.,1973