1. ASTM E23, Standard test methods for notched bar impact testing of metallic materials, 1988
2. EN 10045/1, Charpy impact test on metallic materials, 1990
3. Pr. EN 10045/2, Part 2, Verification of pendulum type testing machines, 1990
4. ISO R 442, Verification of pendulum impact testing machines for testing steels, 1986