1. ISO 48. Rubber, vulcanized or thermoplastic—Detemination of hardness (hardness between 10 IRHD and 100 IRHD).
2. ISO 7267. Rubber covered rollers. Determination of apparent hardness. Part 3: Pusey and Jones method. ASTM D531. Indentation of rubber by means of the Pusey and Jones plastometer.
3. ISO 7619. Determination of indentation hardness by means of pocket hardness meter.
4. Problems in determining hardness of rigid rubbers