@article{compref19,
   author = {Ashby,WR},
   year = {1973},
   title = {Some Peculiarities of Complex Systems},
   journal = {Cybernetic Medicine},
   volume = {9},
   pages = {1-7}
}

@article{compref20,
   author = {Ashby,WR and Gardner,M},
   year = {1970},
   title = {Connectance of Large, Dynamic Cybernetic Systems: Critical Values for Stability},
   journal = {Nature},
   volume = {228},
   pages = {784}
}

@book{compref18,
   author = {Ashby,WR},
   year = {1964},
   title = {Introduction to Cybernetics},
   publisher = {Methuen},
   address = {New York}
}