An Axiomatics for Categories of Transition Systems as Coalgebras. - Peter T. Johnstone; John Power; Toru Tsujishita; Hiroshi Watanabe 002; James Worrell 001 (LICS, 1998)

Construction of universal modal worlds based on hyperset theory. - Toru Tsujishita (Arch. Math. Log., 1999)

On the structure of categories of coalgebras. - Peter T. Johnstone; John Power; Toru Tsujishita; Hiroshi Watanabe 002; James Worrell 001 (Theor. Comput. Sci., 2001)