@article{Uhlenberg1998,
author = {Uhlenberg, P. and Hammill, B.G.},
title= {Frequency of grandparent contact with grandchild sets: Six factors that make a difference},
year = {1998},
doi = {10.1093/geront/38.3.276},
volume = {38},
number = {3},
pages = {276--285},
}