@article{Brewer1999,
author = {Brewer, D.D. and Webster, C.M.},
title= {Forgetting of friends and its effects on measuring friendship networks},
year = {1999},
doi = {10.1016/S0378-8733(99)00018-0},
journal = {Social Networks},
volume = {21},
number = {4},
pages = {361--373},
}