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Nonnegativity and positivity of quadratic functionals in the discrete calculus of variations: Survey J - Článek v odborném periodikuHILSCHER, Roman a Vera ZEIDAN. Nonnegativity and positivity of quadratic functionals in the discrete calculus of variations: Survey. Journal of Difference Equations and Applications. Taylor and Francis, 2005, roč. 11, č. 9, s. 857-875. ISSN 1023-6198.Podrobněji: https://is.muni.cz/publication/575741/cs