1. Yu. M. Lakhtin, Physical Bases of Nitriding [in Russian], Moscow, Mashgiz (1948).
2. A. V. Ryabchenkov and V. D. Yakhnina, Collection TsNIITMASh, No. 11, Moscow, Mashgiz (1948).
3. I. V. Samoilov, Metallovedenie i termicheskaya obrabotka (1959), No. 8.
4. S. Benedic, ?Machine ? (1962), No. 6.
5. H. Laplanche, ?Metallurgie et constr. mec. ? (1963), No. 3.