2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/171027Borodin et al figured out a gap of the paper published at J. Combinatorial Theory Ser. B (Vol.96 (2006) 958--963), and gave a new proof with the similar technique. The purpose of this note is to fix the gap by slightly revising the definition of special faces, and adding a few lines of explanation in the proofs (new added text are all in black font).6 pagesCombinatoricstext