Labuschagne W (2013): Belief Revision and Verisimilitude, Otago Logic Group meeting on 29 July 2013, University of Otago.

Labuschagne W and Heidema J (2012 a): Towards Agent-Oriented Logic 1, Otago Logic Group meeting on 23 Apr 2012, University of Otago.

Labuschagne W (2012 b): Towards Agent-Oriented Logic 2, Otago Logic Group meeting on 14 May 2012, University of Otago.

Britz K, Heidema J, and Labuschagne WA (2007): Entailment, duality, and the forms of reasoning. Technical Report OUCS–2007–01.

Britz K, Heidema J and Labuschagne WA (2006): A modal perspective on defeasible reasoning. Preprint of 2007 SAMS conference paper.

Ferguson D and Labuschagne WA (2001): A preferential semantics for epistemic logic. Technical Report OUCS–2001–09.

Meyer T, Labuschagne WA and Heidema J (1998): Refined epistemic entrenchment. Research Report 264/98(10), Department of Mathematics, Applied Mathematics, and Astronomy, University of South Africa.

Meyer T, Labuschagne WA and Heidema J (1998): A semantic weakening of the recovery postulate for theory contraction. Research Report 258/98(4), Department of Mathematics, Applied Mathematics, and Astronomy, University of South Africa.

Meyer T, Labuschagne WA and Heidema J (1998): Intensional semantic base change: A first approximation. Research Report 255/98(1), Department of Mathematics, Applied Mathematics, and Astronomy, University of South Africa.

Meyer T, Labuschagne WA and Heidema J (1997): A semantic approach to theory change. Research Report 246/97(12), Department of Mathematics, Applied Mathematics, and Astronomy, University of South Africa.

Meyer T, Labuschagne WA and Heidema J (1996): Conditional plausibility by power–orders using s–models. Research Report 232/96(11), Department of Mathematics, Applied Mathematics, and Astronomy, University of South Africa.

Meyer T, Labuschagne WA and Heidema J (1995): Plausibility by power–order semantics. Research Report 210/95(16), Department of Mathematics, Applied Mathematics, and Astronomy, University of South Africa.

Meyer T, Labuschagne WA and Heidema J (1995): Power–orderings as a generalisation of minimal model semantics. Research Report 196/95(2), Department of Mathematics, Applied Mathematics, and Astronomy, University of South Africa.

Meyer T, Labuschagne WA and Heidema J (1995): On the probabilistic intuition underlying circumscription. Research Report 195/95(1), Department of Mathematics, Applied Mathematics, and Astronomy, University of South Africa.

Burger IC, Heidema J, Labuschagne WA, Meyer T and van Wyk B–E (1994): Gradogramme — 'n Nuwe hulpmiddel vir kladistiese taksonomie. Research Report 183/94(11), Department of Mathematics, Applied Mathematics, and Astronomy, University of South Africa.

Heidema J and Labuschagne W (1991): Compatibility in deductive databases. Research Report 5/91, Department of Mathematics, Rand Afrikaans University.

Heidema J, Labuschagne W and Pistorius M (1991): Boolean prediction analysis revisited. Research Report 3/91, Department of Mathematics, Rand Afrikaans University.

Heidema J and Labuschagne WA (1988): The measurement of semantic information. Research Report 2/88, Department of Mathematics, Rand Afrikaans University.

Labuschagne WA and Heidema J (1986): An infinitary language adequate for axiomatising topology. Research Report 7/86, Department of Mathematics, Rand Afrikaans University.

Heidema J and Labuschagne WA (1980): First-order topology. In Brummer GCL and Hardie KA (eds): Session on Categorical Algebra and Topology: Preprint collection arising from a special session of the South African Mathematical Society, University of Cape Town, 29-31 Oct 1979, 121-129.