Knopfmacher, A., Odlyzko, A. M., Pittel, B., Richmond, L. B., Stark, D., Szekeres, G., & Wormald, N. C. (1998). The Asymptotic Number of Set Partitions with Unequal Block Sizes. The Electronic Journal of Combinatorics, 6(1), R2. https://doi.org/10.37236/1434