@article{Seeman1988,
author = {Seeman, T.E. and Berkman, L.F. },
title= {Structural characteristics of social networks and their relationship with social support in the elderly: who provides support},
year = {1988},
doi = {10.1016/0277-9536(88)90065-2},
journal = {Soc Sci Med },
volume = {26},
number = {7},
pages = {737−749},
}