• On approximation processes defined by the cosine operator function in a Banach spaceSaksa, Anna; Kivinukk, AndiInternational Conference : Harmonic Analysis and Approximations, VII, Dedicated to 90th Anniversary of Alexandr Talalyan, 16-22 September, 2018 Tsaghkadzor, Armenia : abstracts2018 / p. 95-96 http://mathconf.sci.am/haa2018/images/HAAVIIAbstractsBook.pdf