Verna Gardiner, Roger B. Lazarus, Nicholas Metropolis, Stanisław Marcin Ulam: On certain sequences of integers defined by sieves. In: Mathematics Magazine. 29. Jahrgang, Nr.3, 1956, ISSN0025-570X, S.117–122, doi:10.2307/3029719.
Verna Gardiner, Roger B. Lazarus, Nicholas Metropolis, Stanisław Marcin Ulam: On certain sequences of integers defined by sieves. In: Mathematics Magazine. 29. Jahrgang, Nr.3, 1956, ISSN0025-570X, S.117–122, doi:10.2307/3029719.