1. Yu. M. Lakhtin, “Surface hardening of steels and alloys,” Metalloved. Term. Obrab. Met., No. 11, 14 – 25 (1988).
2. V. I. Shapochkin, E. I. Tesker, and L. M. Semenova, “Effect of the surface layer on the galling of thermochemically treated gears,” Met. Sci. Heat Treat., 27(3), 544 – 547 (1985).
3. B. Edenhofer, “An overview of advances in atmosphere and vacuum heat treatment,” Heat Treat. Metals, 26(1), 1 – 5 (1999).
4. W. Grafen and B. Edenhofer, “Acetylene low-pressure carburizing – a novel and superior carburizing technology,” Heat Treat. Metals, 26(4), 79 – 85 (1999).
5. A. E. Smirnov and M. Yu. Semenov, “Application of vacuum thermal and thermochemical treatment for hardening heavily-loaded machine components, instruments, and tools,” Electronic Journal “Nauka I Obrazovaniye,” MGTU im. Baumana, No. 2 (2014), access date — May 15, 2019.