Kopanev Sergey Anatolievich, Borisova Yana Vladimirovna, Kolesnikov Ivan Alexandrovich «On small variation formulas» // Tomsk State University Journal of Mathematics and Mechanics 2017. №49 C.5-15
Copanev Sergey Anatol'evich «A note on the curvature of the level line under the conformal mapping» // 2013. № 3(23) C.34-36
