* {{Cite book |author1=Harary, Frank |author2=Palmer, Edgar M. | title=Graphical enumeration | date=1973 | publisher=New York, Academic Press | location= | isbn=0-12-324245-2 | pages=}} | * {{Cite book |author1=Harary, Frank |author2=Palmer, Edgar M. | title=Graphical enumeration | date=1973 | publisher=New York, Academic Press | location= | isbn=0-12-324245-2 | pages=}} |