Freksa, Christian. 1992. “Temporal Reasoning Based on Semi-Intervals.”Artificial Intelligence 54(1–2): 199–227.
Freksa, Christian. 1996. “Erratum to Freksa (1992).”Artificial Intelligence 87(1–2): 387.
Freksa, Christian, Habel, Christopher and Wender, Karl F., eds. 1998. Spatial Cognition: An Interdisciplinary Approach to Representing and Processing Spatial Knowledge. Berlin: Springer.