@incollection{compref159,
   author = {Heylighen,F},
   year = {1990},
   title = {Relational Closure: a Mathematical Concept for Distinction-making and complexity analysis},
   booktitle = {Cybernetics and Systems '90},
   editor = {Trappl,R},
   publisher = {World Scientific},
   address = {Singapore},
   pages = {335-341}
}