C. F. Chang J. X. Chang X. C. Lu Peter Che Bor Lam J. F. Wang Edge-Face Total Chromatic Number of Outerplanar Graphs with Delta(G)=6. 396-399 1995 conf/cocoon/1995 COCOON db/conf/cocoon/cocoon95.html#ChangCLLW95 http://dx.doi.org/10.1007/BFb0030858