On q-graphs. - Chong-Yun Chao; Zhi-Yi Guo; Nian-Zu Li (Discret. Math., 1997)

On T-chromatic uniqueness of graphs. - Zhi-Yi Guo (Discret. Math., 1997)

Chromaticity of a family of K4 homeomorphs. - Zhi-Yi Guo; Earl Glen Whitehead Jr. (Discret. Math., 1997)