p, q-Stirling numbers and set partition statistics. - Michelle L. Wachs; Dennis White (J. Comb. Theory A, 1991)

Partition statistics on permutations. - Paul H. Edelman; Rodica Simion; Dennis White (Discret. Math., 1992)

Permutations with roots. - Miklós Bóna; Andrew McLennan; Dennis White (Random Struct. Algorithms, 2000)