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2. On a class of linear difference-integral equations;Anselove;Arch. Ration. Mech. Anal.,1963
3. On some Volterra integral equations of which all solutions are convergent;De Bruijn,1950
4. On the number of positive integers ⩽x and free of prime factors >y;De Bruijn,1951
5. On some linear functional equations;De Bruijn;Publ. Math. Debrecen,1950