Kaptay, G. “Surface Grain Coarsening and Surface Softening During Machining of Ultra-Fine Grained Titanium”. Journal of Mining and Metallurgy, Section B: Metallurgy, Vol. 48, no. 3, Dec. 2012, p. 449, https://aseestant.ceon.rs/index.php/jmm/article/view/2859.