Hiroaki Takai Takashi Kanatani Akira Matsubayashi Path Coloring on Binary Caterpillars. 1906-1913 2006 89-D IEICE Transactions 6 http://dx.doi.org/10.1093/ietisy/e89-d.6.1906 db/journals/ieicet/ieicet89d.html#TakaiKM06