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2. 2. V. M. Bondarenko, M. V. Styopochkina, "(Min, max)-equivalence of posets and quadratic Tits form," in: Problems of Analysis and Algebra: Zb. Pr. Inst. Mat. Nats. Akad. Nauk Ukr., 2, No. 3, 18-58 (2005) (in Russian).
3. 3. V. M. Bondarenko, M. V. Stepochkina, "Description of posets critical with respect to the nonnegativity of the quadratic Tits form," Ukr. Mat. Zh., 61, No. 5, 611-624 (2009)
4. English translation: Ukr. Math. J., 61, No. 5, 734-746 (2009),
5. 4. V. M. Bondarenko, M. V. Styopochkina, "On properties of the Hasse diagram of nonserial posets with positive quadratic Tits form," Nauk. Visn. Uzhgorod. Univ., Ser. Mat. Inf., 29, No. 2, 31-34 (2016).