1. ASTM, American Society for Testing Materials, ASTM D-2234, ASTM D-2103, ASTM D-3172, ASTM D-3174, ASTM D-3175, ASTM D-3177, 1993.
2. ASTM D409/D409M-16, Standard Test Method for Grindability of Coal by the Hardgrove-Machine Method, ASTM International, West Conshohocken, PA, 2016, https://doi.org/10.1520/D0409_D0409M-16.
3. ACARP Report: The Hardgrove Grindability index. ISSUE No 5 February 1998.
4. An analysis of ball-and-race milling. Part I. The Hardgrove mill;Austin;Powder Technol.,1981
5. Development of Crusher Models Using Laboratory Particle Breakage Data,;Awachie,1983