TY JOUR TI TWO-STAGE SIGNATURE RESEARCH: VARIABILITY OR IMPERATIVE KW signature research methods; two-stage; solving the issue of the authetivity of the signature; types of inauthentic signatures; features displayed in inauthentic signature; establishing the author of an inauthentic signature; the problem of comparability of samples JO FORENSIC EXAMINATION AU Ismatova, T.I. PY 2025 IS 0 PB Volgograd Academy of the Ministry of Internal Affairs of Russia