1. Selecting Additives to Improve Machinability of Ferrous PM Parts;Trudel,1984
2. Sulphur-Free Iron Powder Machinable Grade;Gagné,1989
3. Improved Machinability of PM Parts for Demanding Applications;Poirier,1989
4. W R Backer, Principles of Machining, American Society for Metals, Chapter 2, pp 14–16.