Grandis, M. (2006). Modelling fundamental 2-categories for directed homotopy, Homology Homotopy Appl. 8, 31–70.
Grandis, M. (2006). Lax 2-categories and directed homotopy, Cah. Topol. G ́eom. Diff ́er. Cat ́eg. 47, 107–128.
Grandis, M. (2006). Absolute lax 2-categories, Appl. Categ. Struc- tures 14, 191–214.