Toward an Understanding of Data Structures
This paper presents a notation and formalism
for describing the semantics of data structures. 
 This is based on directed graphs with named edges and
transformations on these graphs.  In addition, 
an implementation facility is described which could
be part of a programming language, which allows a 
programmer who has expressed the semantics of an algorithm
in terms of the graphs to then specify the 
implementation of some of his data structures in order to gain efficiency.
CACM October,1971
Earley, J.
