==== BibTeX ==== @article{CG2009 , author = {Markus Chimani and Carsten Gutwenger} , title = {Non-Planar Core Reduction of Graphs} , journal = {Discrete Mathematics} , volume = {309} , number = {7} , pages = {1838--1855} , year = {2009} , doi = {10.1016/j.disc.2007.12.078} }