What was Nicolo Tartaglia doing in the night to Ash Wednesday of the year 1523 in Verona. (Was machte Nicolo Tartaglia in der Nacht zum Aschermittwoch des Jahres 1523 in Verona.) Lüneburg, Heinz (1991) Séminaire Lotharingien de Combinatoire [electronic only]
Where the typical set partitions meet and join. Pittel, Boris (2000) The Electronic Journal of Combinatorics [electronic only]