Encyclopaedia of Mathematical Sciences <br/><br/>
Low dimensional Topology II  graphs on surfaces and their applications 
Sergei K. Lando and Alexander K. Zvonkin 
 - Berlin  Springer-Verlag  2004 
 - xv, 455p. Bibl. Index. 
 - Encyclopaedia of Mathematical Sciences   V. 141 .
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<br/><br/><label>ISBN: </label>3540002030 
<br/><br/><label>Dewey Class. No.: </label>510.3  / En56.141