Zi-Xia Song A further extension of Yap's construction for ?-critical graphs. [Citation Graph (0, 0)][DBLP] Discrete Mathematics, 2002, v:243, n:1-3, pp:283-290 [Journal]
Zi-Xia Song, H. P. Yap Chromatic Index Critical Graphs of Even Order with Five Major Vertices. [Citation Graph (0, 0)][DBLP] Graphs and Combinatorics, 2005, v:21, n:2, pp:239-246 [Journal]