1. (1) ISO 6507. Metallic Materials—Vickers Hardness Test—, (1997).
2. (2) ISO 6508. Metallic Materials—Rockwell Hardness Test—, (1999).
3. (3) ISO 6506. Metallic Materials—Brinell Hardness Test—, (1999).
4. (4) ISO 4545. Metallic Materials—Hardness Test—Knoop test, (1993).
5. (5) G. M. Pharr and W. C. Oliver: MRS Bulletin, 17(1992), 28-33.