1. On the set of divisors of a number;de Brudn;Nieuw Arch. Wiskunde,1951
2. Sur le nombre des fonctions Booleennes monotones de n variables;Hansel;C. R. Acad. Sci. Paris,1966
3. On a conjecture of Erdös and a stronger form of Sperner's theorem;Katona;Studia Sci. Math. Hungar.,1966
4. On a lemma of Littlewood and Offord on the distribution of certain sums;Kleitman;Math. Z.,1965