• On optimal recovery of functions satisfying given boundary conditionsLevin, MeišeEesti NSV Teaduste Akadeemia toimetised. Füüsika. Matemaatika = Известия Академии наук Эстонской ССР. Физика. Математика = Proceedings of Academy of Sciences of the Estonian SSR. Physics. Mathematics1979 / lk. 9-16 https://www.ester.ee/record=b1264310*est