OWL newbie Question

Hello out there,
I am currently trying to perform my first steps in the OWL world. Since 
searching for a simple and useful example I want to build up the ACM 
classification index in OWL. My approach is to express each  classification 
entry as an owl:class concept, relating them via rdfs:subClassOf. That is 
pretty simple. However the ACM classification index encodes references 
between certain entries too (e.g. B.2.3 ["Reliability, Testing, and 
Fault-Tolerance Reliability, Testing, and Fault-Tolerance"] is related to B.8 
["Performance and Reliability"]) . So my question here is how to model those 
references in OWL. I believe using the equivalentClass construct is not 
appropriate, because those classes have not same instances. 
Could anybody give me an enlightening idea please?

thanks in advance 

Michael Engelhardt

.me