Bill Sands. Counting antichains in finite partially ordered sets. Discrete Mathematics, 35(1-3):213-228, 1981. [doi]
@article{Sands81,
title = {Counting antichains in finite partially ordered sets},
author = {Bill Sands},
year = {1981},
doi = {10.1016/0012-365X(81)90210-7},
url = {http://dx.doi.org/10.1016/0012-365X(81)90210-7},
researchr = {https://researchr.org/publication/Sands81},
cites = {0},
citedby = {0},
journal = {Discrete Mathematics},
volume = {35},
number = {1-3},
pages = {213-228},
}