@article{Bernard1991,
author = {Bernard, H.R. and Johnsen, E.C. and Killworth, P.D. and Robinson, S.},
title= {Estimating the size of an average personal network and of an event subpopulation: Some empirical results},
year = {1991},
doi = {10.1016/0049-089X(91)90012-R},
volume = {20},
number = {2},
pages = {109--121},
}