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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. 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) (in Russian)
4. English translation: Ukr. Math. J., 61, No. 5, 734-746 (2009), https://doi.org/10.1007/s11253-009-0245-6
5. V. M. Bondarenko, M. V. Styopochkina, "On properties of the Hasse diagram of nonserial posets with positive quadratic Tits form," Nauk. Visn. Uzhhorod. Univ., Ser. Mat. Inf., 29, No. 2, 31-34 (2016).