@article{compref9,
   author = {Albin,PS and Gottinger,HW},
   year = {1983},
   title = {Structure and Complexity in Economic and Social Systems},
   journal = {Mathematical Social Sciences},
   volume = {5},
   pages = {253-268}
}

@article{compref8,
   author = {Albin,PS},
   year = {1980},
   title = {The Complexity of Social Groups and Social Systems by Graph Structures},
   journal = {Mathematical Social Sciences},
   volume = {1},
   pages = {101-129}
}