1. On the o-spektrum of regular operators and the spectrum of measures
2. Factorization by lattice homomorphisms
3. Arendt, W. and Hart, D. R. The spectrum of quasi-invertible disjointness preserving operators. To appear in J. Functional Analysis
4. Arendt, W. and Sourour, A. R. Perturbation of regular operators and the order essential spectrum. To appear in Indagationes Mathematicae
5. Operators of Riesz type