Stable Homotopy Monomorphisms. - R. W. Kieboom (Appl. Categorical Struct., 1997)

A Homotopy 2-Groupoid of a Hausdorff Space. - Keith A. Hardie; Klaus Heiner Kamps; R. W. Kieboom (Appl. Categorical Struct., 2000)

A Homotopy Bigroupoid of a Topological Space. - Keith A. Hardie; Klaus Heiner Kamps; R. W. Kieboom (Appl. Categorical Struct., 2001)